Processes for intermediates for macrocyclic compounds

ABSTRACT

The present invention is directed to novel macrocyclic compounds of formula (I) and their pharmaceutically acceptable salts, hydrates or solvates: 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , n 1 , m, p Z 1 , Z 2 , and Z 3  are as describe in the specification. The invention also relates to compounds of formula (I) which are antagonists of the motilin receptor and are useful in the treatment of disorders associated with this receptor and with or with motility dysfunction.

RELATED APPLICATION INFORMATION

This application is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 10/872,142, filed Jun. 18, 2004, currently pending, which claims the benefit of U.S. Patent Application Ser. No. 60/479,223, filed Jun. 18, 2003. The disclosure of each application is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to novel conformationally-defined macrocyclic compounds, pharmaceutical compositions comprising same and intermediates used in their manufacture. More particularly, the invention relates to macrocyclic compounds that have been demonstrated to selectively antagonize the activity of the motilin receptor. The invention further relates to macrocyclic compounds useful as therapeutics for a range of gastrointestinal disorders, in particular those in which malfunction of gastric motility or increased motilin secretion is observed, such as hypermotilinemia, irritable bowel syndrome and dyspepsia.

BACKGROUND OF THE INVENTION

A number of peptide hormones are involved in the control of the different functions in the gastrointestinal (GI) tract, including absorption, secretion, blood flow and motility (Mulvihill, et al. in Basic and Clinical Endocrinology, 4^(th) edition, Greenspan, F. S.; Baxter, J. D., eds., Appleton & Lange: Norwalk, Conn., 1994, pp 551-570). Since interactions between the brain and GI system are critical to the proper modulation of these functions, these peptides can be produced locally in the GI tract or distally in the CNS.

One of these peptide hormones, motilin, a linear 22-amino acid peptide, plays a critical regulatory role in the GI physiological system though governing of fasting gastrointestinal motor activity. As such, the peptide is periodically released from the duodenal mucosa during fasting in mammals, including humans. More precisely, motilin exerts a powerful effect on gastric motility through the contraction of gastrointestinal smooth muscle to stimulate gastric emptying, decrease intestinal transit time and initiate phase III of the migrating motor complex in the small bowel (Itoh, Z., Ed., Motilin, Academic Press: San Diego, Calif., 1990, ASIN: 0123757304; Nelson, D. K. Dig. Dis. Sci. 1996, 41, 2006-2015; Peeters, T. L.; Vantrappen, G.; Janssens, J. Gastroenterology 1980, 79, 716-719).

Motilin exerts these effects through receptors located predominantly on the human antrum and proximal duodenum, although its receptors are found in other regions of the GI tract as well (Peeters, T. L.; Bormans, V.; Vantrappen, G. Regul. Pept. 1988, 23, 171-182). Therefore, motilin hormone is involved in motility of both the upper and lower parts of the GI system (Williams et al. Am. J. Physiol. 1992, 262, G50-G55). In addition, motilin and its receptors have been found in the CNS and periphery, suggesting a physiological role in the nervous system that has not yet been definitively elucidated (Depoortere, I.; Peeters, T. L. Am. J. Physiol. 1997, 272, G994-999 and O'Donohue, T. L et al. Peptides 1981, 2, 467-477). For example, motilin receptors in the brain have been suggested to play a regulatory role in a number of CNS functions, including feeding and drinking behavior, micturition reflex, central and brain stem neuronal modulation and pituitary hormone secretion (Itoh, Z. Motilin and Clinical Applications. Peptides 1997, 18, 593-608; Asakawa, A.; Inui, A.; Momose, K.; et al., M. Peptides 1998, 19, 987-990 and Rosenfeld, D. J.; Garthwaite, T. L. Physiol. Behav. 1987, 39, 753-756). Physiological studies have provided confirmatory evidence that motilin can indeed have an effect on feeding behavior (Rosenfeld, D. J.; Garthwaite, T. L. Phys. Behav. 1987, 39, 735-736).

The recent identification and cloning of the human motilin receptor (WO 99/64436) has simplified and accelerated the search for agents which can modulate its activity for specific therapeutic purposes.

Due to the critical and direct involvement of motilin in control of gastric motility, agents that either diminish (hypomotility) or enhance (hypermotility) the activity at the motilin receptor, are a particularly attractive area for further investigation in the search for new effective pharmaceuticals towards these indications.

Peptidic agonists of the motilin receptor, which have clinical application for the treatment of hypomotility disorders, have been reported (U.S. Pat. Nos. 5,695,952; 5,721,353; 6,018,037; 6,380,158; 6,420,521, U.S. Appl. 2001/0041791, WO 98/42840; WO 01/00830 and WO 02/059141). Derivatives of erythromycin, commonly referred to as motilides, have also been reported as agonists of the motilin receptor (U.S. Pat. Nos. 4,920,102; 5,008,249; 5,175,150; 5,418,224; 5,470,961; 5,523,401, 5,554,605; 5,658,888; 5,854,407; 5,912,235; 6,100,239; 6,165,985; 6,403,775).

Antagonists of the motilin receptor are potentially extremely useful as therapeutic treatments for diseases associated with hypermotility and hypermotilinemia, including irritable bowel syndrome, dyspepsia, gastroesophogeal reflux disorders, Crohn's disease, ulcerative colitis, pancreatitis, infantile hypertrophic pyloric stenosis, diabetes mellitus, obesity, malabsorption syndrome, carcinoid syndrome, diarrhea, atrophic colitis or gastritis, gastrointestinal dumping syndrome, postgastroenterectomy syndrome, gastric stasis and eating disorders leading to obesity.

A variety of peptidic compounds have been described as antagonists of the motilin receptor (Depoortere, I.; Macielag, M. J.; Galdes, A.; Peeters, T. L. Eur. J. Pharmacol. 1995, 286, 241-247; U.S. Pat. Nos. 5,470,830; 6,255,285; 6,586,630; 6,720,433; U.S. 2003/0176643; WO 02/64623). These peptidic antagonists suffer from the known limitations of peptides as drug molecules, in particular poor oral bioavailability and degradative metabolism.

Cyclization of peptidic derivatives is a method employed to improve the properties of a linear peptide both with respect to metabolic stability and conformational freedom. Cyclic molecules tend to be more resistant to metabolic enzymes. Such cyclic tetrapeptide motilin antagonists have been reported (Haramura, M. et al J. Med. Chem. 2002, 45, 670-675, U.S. 2003/0191053; WO 02/16404).

Other motilin antagonists, which are non-peptidic and non-cyclic in nature have also been reported (U.S. Pat. Nos. 5,972,939; 6,384,031; 6,392,040; 6,423,714; 6,511,980; 6,624,165; 6,667,309; U.S. 2002/0111484; 2001/041701; 2002/0103238; 2001/0056106, 2002/0013352; 2003/0203906 and 2002/0002192)

The macrocyclic motilin antagonists of the present invention comprise elements of both peptidic and non-peptidic structures in a combination which has not been pursued for this application previously.

Indeed, the structural features of antagonists of the present invention are different. In particular, within the known motilin antagonists which are cyclic peptides, it was found that such derivatives containing D-amino acids were devoid of activity. In contrast, for the tripeptidomimetic compounds of the present invention, the D-stereochemistry is required for two of the three building elements.

The motilin antagonists of the present invention are also distinct from the prior art in that they comprise a tether element to fulfill the dual role of controlling conformations and providing additional sites for interaction either through hydrophobic interactions, hydrogen bonding or dipole-dipole interactions.

SUMMARY OF THE INVENTION

In a first aspect, the present invention is directed to compounds of formula (I):

and pharmaceutically acceptable salts, hydrates or solvates thereof wherein: Z₁, Z₂ and Z₃ are independently selected from the group consisting of O, N and NR₁₀, wherein R₁₀ is selected from the group consisting of hydrogen, lower alkyl, and substituted lower alkyl; R₁ is independently selected from the group consisting of lower alkyl substituted with aryl, lower alkyl substituted with substituted aryl, lower alkyl substituted with heteroaryl and lower alkyl substituted with substituted heteroaryl; R₂ is hydrogen; R₃ is independently selected from the group consisting of alkyl and cycloalkyl with the proviso that when Z₁ is N, R₃ can form a four, five, six or seven-membered heterocyclic ring together with Z₁; R₄ is hydrogen; R₅ and R₆ are independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocyclic, substituted heterocyclic, aryl, substituted aryl, heteroaryl and substituted heteroaryl, with the proviso that at least one of R₅ and R₆ is hydrogen; X is selected from the group consisting of O, NR₈, and N(R₉)₂ ⁺;

-   -   wherein R₈ is selected from the group consisting of hydrogen,         lower alkyl, substituted lower alkyl, formyl, acyl,         carboxyalkyl, carboxyaryl, amido, sulfonyl, sulfonamido and         amidino; and     -   R₉ is selected from the group consisting of hydrogen, lower         alkyl, and substituted lower alkyl;         m, n₁ and p are independently selected from 0, 1 or 2; and         T is a bivalent radical of formula II:

—U—(CH₂)_(d)—W—Y-Z-(CH₂)_(e)—  (II)

-   -   wherein d and e are independently selected from 0, 1, 2, 3, 4 or         5;     -   wherein U is bonded to X of formula (I) and is —CH₂— or —C(═O)—;     -   wherein Y and Z are each optionally present;     -   W, Y and Z are independently selected from the group consisting         of: —O—, —NR₂₈—, —S—, —SO—, —SO₂—, —C(═O)—, —C(═O)—O—,         —O—C(═O)—, —C(═O)—NH—, —NH—C(═O)—, —SO₂—NH—, —NH—SO₂—,         —CR₂₉R₃₀—, —CH═CH— with a configuration Z or E, and —C≡C—, or         from a ring structure independently selected from the group

-   -   wherein any carbon atom contained within said ring structure,         can be replaced by a nitrogen atom, with the proviso that if         said ring structure is a monocyclic ring structure, it does not         comprise more than four nitrogen atoms and if said ring         structure is a bicyclic ring structure, it does not comprise         more than six nitrogen atoms;     -   G₁ and G₂ each independently represent a covalent bond or a         bivalent radical selected from the group consisting of —O—,         —NR₄₁—, —S—, —SO—, —SO₂—, —C(═O)—, —C(═O)—O—, —O—C(═O)—,         —C(═O)NH—, —NH—C(═O)—, —SO₂—NH—, —NH—SO₂—, —CR₄₂R₄₃—, —CH═CH—         with a configuration Z or E, and —C≡C—; with the proviso that G₁         is bonded closer to U than G₂;     -   K₁, K₂, K₃, K₄, K₆, K₁₅ and K₁₆ are independently selected from         the group consisting of O, NR₄₄ and S;     -   f is selected from 1, 2, 3, 4, 5 or 6;     -   R₃₁, R₃₂, R₃₈, R₃₉, R₄₈ and R₄₉ are independently selected from         hydrogen, halogen, alkyl, substituted alkyl, cycloalkyl,         substituted cycloalkyl, heterocyclic, substituted heterocyclic,         aryl, substituted aryl, heteroaryl, substituted heteroaryl,         hydroxy, alkoxy, aryloxy, amino, halogen, formyl, acyl, carboxy,         carboxyalkyl, carboxyaryl, amido, carbamoyl, guanidino, ureido,         amidino, cyano, nitro, mercapto, sulfinyl, sulfonyl and         sulfonamido; and     -   R₃₃, R₃₄, R₃₅, R₃₆, R₃₇, R₄₇, R₅₀ and R₅₁ are independently         selected from hydrogen, halogen, alkyl, substituted alkyl,         cycloalkyl, substituted cycloalkyl, heterocyclic, substituted         heterocyclic, aryl, substituted aryl, heteroaryl, substituted         heteroaryl, hydroxy, alkoxy, aryloxy, oxo, amino, halogen,         formyl, acyl, carboxy, carboxyalkyl, carboxyaryl, amido,         carbamoyl, guanidino, ureido, amidino, cyano, nitro, mercapto,         sulfinyl, sulfonyl and sulfonamido.

In a second aspect, the invention also proposes compounds of formula (1) which are antagonists of the motilin receptor.

In a third aspect, the invention proposes a method of treating a disorder associated with the motilin receptor or motility dysfunction in humans and other mammals comprising administering a therapeutically effective amount of a compound of formula (1).

While the invention will be described in conjunction with example embodiments, it will be understood that it is not intended to limit the scope of the invention to such embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Preferably in formula (I), as depicted hereinabove, R₁ is selected from the group consisting of —(CH₂)_(q)R₁₁, and —CHR₁₂R₁₃

-   -   wherein q is 0, 1, 2 or 3; and     -   R₁₁ and R₁₂ are independently selected from a ring structure         from the following group:

-   -   wherein any carbon atom in said ring structure can be replaced a         nitrogen atom, with the proviso that if said ring structure is a         monocyclic ring structure, it does not comprise more than four         nitrogen atoms and if said ring structure is a bicyclic ring         structure, it does not comprise more than six nitrogen atoms;     -   A₁, A₂, A₃, A₄ and A₅ are each optionally present and are         independently selected from the group consisting of halogen,         alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl,         heterocyclic, substituted heterocyclic, aryl, substituted aryl,         heteroaryl, substituted heteroaryl, hydroxy, alkoxy, aryloxy,         amino, halogen, formyl, acyl, carboxy, carboxyalkyl,         carboxyaryl, amido, carbamoyl, guanidino, ureido, amidino,         cyano, nitro, mercapto, sulfinyl, sulfonyl and sulfonamido;     -   B₁, B₂, B₃, and B₄ are independently selected from NR₁₄, S or O,         wherein R₁₄ is selected from the group consisting of hydrogen,         alkyl, substituted alkyl, formyl, acyl, carboxyalkyl,         carboxyaryl, amido, sulfonyl and sulfonamido;     -   R₁₃ is as defined for as R₁₁ and R₁₂ or is selected from the         group comprising lower alkyl, substituted lower alkyl, hydroxy,         alkoxy, aryloxy, amino, carboxy, carboxyalkyl, carboxyaryl, and         amido.         wherein A₁, A₂, A₃, A₄ and A₅ are most preferably selected from         halogen, trifluoromethyl, C₁₋₆ alkyl or C₁₋₆ alkoxy.

Preferably, R₁₁, R₁₂ and R₁₃ are selected from the group consisting of:

wherein R_(a) and R_(b) are chosen from the group consisting of Cl, F, CF₃, OCH₃, OH, and C(CH₃)₃ and CH₃.

Also preferably, R₃ in formula (I), is selected from the group consisting of:

-   -   —(CH₂)_(s)CH₃, —CH(CH₃)(CH₂)_(t)CH₃, —CH(OR₁₅)CH₃, —CH₂SCH₃         —CH₂CH₂SCH₃, —CH₂S(═O)CH₃, —CH₂CH₂S(═O)CH₃, —CH₂S(═O)₂CH₃,         —CH₂CH₂S(═O)₂CH₃, —(CH₂)_(u)CH(CH₃)₂, —C(CH₃)₃, and         —(CH₂)_(y)—R₂₁, wherein:         -   s and u are independently selected from 0, 1, 2, 3, 4 or 5;         -   t is independently selected from 1, 2, 3 or 4;         -   y is selected from 0, 1, 2, 3 or 4;         -   R₁₅ is selected from the group consisting of hydrogen,             alkyl, substituted alkyl, formyl and acyl;         -   R₂₁ is selected from a ring structure selected from the             following group:

-   -   -   wherein any carbon atom in said ring structure can be             replaced by a nitrogen atom, with the proviso that if said             ring structure is a monocyclic ring structure, it does not             comprise more than four nitrogen atoms and if said ring             structure is a bicyclic ring structure, it does not comprise             more than six nitrogen atoms;         -   z is selected from 1, 2, 3, 4 or 5;         -   E₁, E₂ and E₃ are each optionally present and are             independently selected from the group consisting of halogen,             alkyl, substituted alkyl, cycloalkyl, substituted             cycloalkyl, heterocyclic, substituted heterocyclic, aryl,             substituted aryl, heteroaryl, substituted heteroaryl,             hydroxy, alkoxy, aryloxy, amino, halogen, formyl, acyl,             carboxy, carboxyalkyl, carboxyaryl, amido, carbamoyl,             guanidino, ureido, amidino, cyano, nitro, mercapto,             sulfinyl, sulfonyl and sulfonamido; and         -   J is optionally present and is selected from the group             consisting of alkyl, substituted alkyl, cycloalkyl,             substituted cycloalkyl, heterocyclic, substituted             heterocyclic, aryl, substituted aryl, heteroaryl,             substituted heteroaryl, hydroxy, alkoxy, aryloxy, oxo,             amino, halogen, formyl, acyl, carboxy, carboxyalkyl,             carboxyaryl, amido, carbamoyl, guanidino, ureido, amidino,             mercapto, sulfinyl, sulfonyl and sulfonamido.

The tether portion (T) of formula (I) is preferably selected from the group consisting of:

wherein L₁ is O, NH or NMe; L₂ is CH or N; L₃ is CH or N; L₄ is O or CH₂; L₅ is CH or N L₆ is CR₅₂R₅₃ or O; R₄₆ is H or CH₃; R₅₂, R₅₃, R₅₄, R₅₅, R₅₆ and R₅₇ are independently selected from hydrogen, lower alkyl, substituted lower alkyl, hydroxy, alkoxy, aryloxy, amino, and oxo; or R₅₂ together with R₅₃ or R₅₄ together with R₅₅ or R₅₆ together with R₅₇ can independently form a three to seven-membered cyclic ring comprising carbon, oxygen, sulfur and/or nitrogen atoms; (X) is the site of a covalent bond to X in formula (I); and (Z₃) is the site of a covalent bond to Z₃ in formula (I).

In a particularly preferred embodiment of the invention, there are provided compounds of formula (I) wherein m, n and p are 0, X, Z₁, Z₂ and Z₃ are NH and R₂, R₄ and R₅ are hydrogen, represented by formula (III):

According to another aspect of the invention, there are provided compounds of formula (I) wherein when Z₁ is a nitrogen atom, R₃ forms a four, five, six or seven-membered heterocyclic ring together with Z₁, represented by formula (IV):

wherein said heterocyclic ring may contain a second nitrogen atom, or an oxygen, or sulfur atom; n₂ is selected from 0, 1, 2 or 3 R₇ is optionally present and is selected from the group consisting of alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heterocyclic, substituted heterocyclic, aryl, substituted aryl, heteroaryl, substituted heteroaryl, hydroxy, alkoxy, aryloxy, oxo, amino, halogen, formyl, acyl, carboxy, carboxyalkyl, carboxyaryl, amido, carbamoyl, guanidino, ureido, amidino, mercapto, sulfinyl, sulfonyl and sulfonamido.

It is to be understood, that in the context of the present invention, the terms amino, guanidine, ureido and amidino encompass substituted derivatives thereof as well.

Preferably, the invention provides a method of treating a disorder associated with hypermotility or hypermotilinemia in humans and other mammals comprising administering a therapeutically effective amount of a compound of formula (I).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts Scheme 1 presenting a general synthetic strategy to conformationally-defined macrocycles of the present invention.

FIG. 2 depicts the standard procedure for the synthesis of tether T8 of Example 16.

FIG. 3 depicts the standard procedure for the synthesis of tether T9 of Example 17.

FIG. 4 depicts the standard procedure for the synthesis of Ddz-propargylamine of Example 18.

FIG. 5A depicts the standard procedure for the synthesis of tether T10 of Example 19.

FIG. 5B depicts the second synthetic route to tether T10 of Example 19.

FIG. 6 depicts the standard procedure for the synthesis of Tether T11 of Example 20.

FIG. 7 depicts the standard procedure for the synthesis of tether T12 of Example 26.

FIG. 8 depicts the procedure for synthesis of PPh₃-DIAD adduct of Example 29-C.

FIG. 9 depicts the standard procedure for attachment of tethers via reductive amination of Example 30.

FIG. 10 depicts the standard procedure for the synthesis of tether T28 of Example 32.

FIG. 11 the standard procedure for the synthesis of tether T32 of Example 36.

FIGS. 12A, 12B depict the standard procedure for the synthesis of tether T33a and T33b of Example 37.

FIG. 13 depicts the standard procedure for the synthesis of tether T34 of Example 38.

FIG. 14 depicts the standard procedure for the synthesis of tether T35 of Example 39.

FIG. 15 depicts the standard procedure for the synthesis of tether T36 of Example 40.

FIG. 16 depicts the standard procedure for the synthesis of tether T37 of Example 41.

FIG. 17 depicts the standard procedure for the synthesis of tether T38 of Example 42. Chiral T38 can be accessed through the use of asymmetric synthesis methods, resolution or chiral chromatography techniques available in the literature.

HPLC (standard gradient) t_(R)=8.46 min Chiral material can be accessed by starting with the chiral epoxide. For example, the (S)-isomer of T38 was constructed in 89% overall yield from (S)-propylene oxide.

FIG. 18 depicts the standard procedure for the synthesis of tether T39 of Example 43. Chiral T39 can be accessed through the use of asymmetric synthesis methods, resolution or chiral chromatography techniques available in the literature.

FIG. 19 depicts the standard procedure for the synthesis of tether T40 of Example 44. Chiral T40 can be accessed through the use of asymmetric synthesis methods, resolution or chiral chromatography techniques available in the literature.

FIG. 20 depicts the standard procedure for the synthesis of tether T41 of Example 45.

FIG. 21 depicts the standard procedure for the synthesis of tether T42 of Example 46.

FIG. 22 depicts Scheme 2 of the thioester strategy for macrocyclic compounds of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Although preferred embodiments of the present invention have been described in detail herein and illustrated in the accompanying structures, schemes and tables, it is to be understood that the invention is not limited to these precise embodiments and that various changes and modifications may be effected therein without departing from the scope or spirit of the present invention.

Specifically preferred compounds of the present invention, include, but are not limited to:

In addition to the preferred tethers (T) illustrated previously, other specific tethers employed for compounds of the invention are shown hereinbelow:

In a preferred embodiment, the present invention is directed to a method of treating irritable bowel syndrome, dyspepsia, Crohn's disease, gastroesophogeal reflux disorders, ulcerative colitis, pancreatitis, infantile hypertrophic pyloric stenosis, carcinoid syndrome, malabsorption syndrome, diarrhea, diabetes mellitus, obesity, postgastroenterectomy syndrome, atrophic colitis or gastritis, gastric stasis, gastrointestinal dumping syndrome, celiac disease and eating disorders leading to obesity in humans and other mammals comprising administering a therapeutically effective amount of a compound of formula (I).

Synthetic Methods A. General Information

-   -   Reagents and solvents were of reagent quality or better and were         used as obtained from various commercial suppliers unless         otherwise noted. DMF, DCM and THF used are of DriSolv® (EM         Science, now EMD Chemicals, Inc., part of Merck KgaA, Darmstadt,         Germany) or synthesis grade quality except for (i)         deprotection, (ii) resin capping reactions and (iii) washing.         NMP used for the amino acid (AA) coupling reactions is of         analytical grade. DMF was adequately degassed by placing under         vacuum for a minimum of 30 min prior to use. Tyr(3tBu) was         synthesized following the method reported in JP2000 44595. Cpa         was made using literature methods (Tetrahedron: Asymmetry 2003,         14, 3575-3580) or obtained commercially. Boc- and Fmoc-protected         amino acids and side chain protected derivatives, including         those of N-methyl and unnatural amino acids, were obtained from         commercial suppliers or synthesized through standard         methodologies known to those in the art. Ddz-amino acids were         either synthesized by standard procedures or obtained         commercially from Orpegen (Heidelberg, Germany) or Advanced         ChemTech (Louisville, Ky., USA). Bts-amino acids were         synthesized as described in Example 6. Hydroxy acids were         obtained from commercial suppliers or synthesized from the         corresponding amino acids by literature methods. Analytical TLC         was performed on pre-coated plates of silica gel 60F254 (0.25 mm         thickness) containing a fluorescent indicator. The term         “concentrated/evaporated under reduced pressure” indicates         evaporation utilizing a rotary evaporator under either water         aspirator pressure or the stronger vacuum provided by a         mechanical oil vacuum pump as appropriate for the solvent being         removed. “Dry pack” indicates chromatography on silica gel that         has not been pre-treated with solvent, generally applied on         larger scales for purifications where a large difference in         R_(f) exists between the desired product and any impurities. For         solid phase chemistry processes, “dried in the standard manner”         is that the resin is dried first in air (1 h), and subsequently         under vacuum (oil pump usually) until full dryness is attained         (˜30 min to O/N).

B. Synthetic Methods for Building Blocks of the Invention Example 6 Standard Procedure for the Synthesis of Bts-Amino Acids

-   -   To a solution of the amino acid or amino acid derivative (0.1         mol, 1.0 eq) in 0.25 N sodium hydroxide (0.08 mol, 0.8 eq) with         an initial pH of approximately 9.5 (pH meter) at rt, solid         Bts-Cl (0.11 mol, 1.1 eq) was added in one portion. The         resulting suspension was stirred vigorously for 2-3 d. The pH of         the reaction should be adjusted with 5.0 N sodium hydroxide as         required to remain within the range 9.5-10.0 during this time.         Typically, the pH has to be adjusted every 20-30 min during the         first 5 h. Once the pH stops dropping, it is an indication that         the reaction is almost complete. This can be confirmed by TLC         (EtOAc:MeOH, 95:5). Upon completion, the reaction mixture was         washed with Et₂O. Washing is continued until the absence of         non-polar impurities in the aqueous layer is confirmed by TLC         (typically 3×100 mL). The aqueous solution was then cooled to 0°         C., acidified to pH 2.0 with 1 N HCl until no additional         cloudiness forms, and extracted with EtOAc (3×100 mL).         Alternatively, a mixture of DCM and EtOAc may be used as the         extraction solvent, depending on the solubility of the product         obtained from different amino acids or derivatives. Note that         DCM cannot be used solely as solvent because of the emulsion         formed during extraction. The combined organic phases were         washed with brine (2×150 mL), dried over MgSO₄, filtered and         evaporated under reduced pressure. DCM (1×) and hexanes (2×)         were evaporated from the residue in order to ensure complete         removal of the EtOAc and give the desired compound as a solid in         55-98% yield.     -   The following are modifications that have proven useful for         certain amino acids:     -   Gly, Ala, D-Ala, β-Ala and GABA: Use 1.5 eq of amino acid per eq         of Bts-Cl, in order to prevent dibetsylation.     -   Met: Carry out the reaction under N₂ to prevent oxidation.     -   Gln and Asn: Due to the solubility of Bts-Gln and Bts-Asn, the         work-up required is modified from the standard procedure: Upon         completion of the reaction, the reaction mixture was washed with         diethyl ether. Washing is continued until the absence of         non-polar impurities in the aqueous layer is confirmed by TLC         (typically 3×100 mL). The aqueous phase was then cooled to 0° C.         and acidified to pH 2.0 with 6 N HCl. 6 N HCl was employed to         minimize the volume of the solution due to the water solubility         of Bts-Gln and Bts-Asn. (They are, in contrast, difficult to         dissolve in DCM, EtOAc or chloroform.) The solution was         maintained at 0° C. for 10 min and the product was collected by         filtration as a white precipitate. The solid was washed with         cold water (1×), cold brine (2×) and water (1×, 25° C.). The pH         of this wash was taken, if it is not approximately 4, the solid         was washed again with water. Finally, the solid was washed with         cold EtOAc, then with cold Et₂O (2×), and finally dried under         vacuum (oil pump) (83-85% yield).

C. General Synthetic Strategy to Conformationally-Defined Macrocycles of the Present Invention

The compounds of Formula I can be synthesized using traditional solution synthesis techniques or solid phase chemistry methods. In either, the construction involves four phases: first, synthesis of the building blocks, including one to four moieties, comprising recognition elements for the biological target receptor, plus one tether moiety, primarily for control and definition of conformation. These building blocks are assembled together, typically in a sequential fashion, in a second phase employing standard chemical transformations. The precursors from the assembly are then cyclized in the third stage to provide the macrocyclic structures. Finally, a post-cyclization processing stage involving removal of protecting groups and optional purification then provides the desired final compounds (see FIG. 1). This method has been previously disclosed in WO 01/25257 and U.S. patent application Ser. No. 09/679,331. A general synthetic strategy is shown in FIG. 1.

D. Procedures for the Synthesis of Representative Tethers of the Present Invention

The important tether component required for compounds of the invention are synthesized as described in WO01/25257, U.S. Provisional Pat. Appl. Ser. No. 60/491,248 or herein. A standard procedure for the synthesis of tether B is shown in FIG. 2.

-   Step T8-1: Chlorotrimethylsilane (116 mL, 0.91 mol, 1.5 eq) was     added to a suspension of 2-hydroxycinnamic acid (100 g, 0.61 mol,     1.0 eq) in MeOH (500 mL, HPLC grade) over 30 min at 0° C. The     resulting mixture was stirred at rt O/N. The reaction was monitored     by TLC (EtOAc/MeOH: 98/2). Heating the reaction mixture in a hot     water can accelerate the process if necessary. After the reaction     was completed, the reaction mixture was evaporated under reduced     pressure to afford methyl 2-hydroxycinnamate as a white solid     (108.5 g) in quantitative yield. The identity of this intermediate     compound is confirmed by NMR. This reaction can be carried out on     larger (kg) scale with similar results -   Step T8-2: 3,4-Dihydro-2H-pyran (DHP, 140 mL, 1.54 mol, 2.52 eq) was     added dropwise to 2-bromoethanol (108 mL, 1.51 mol, 2.5 eq) in a 2 L     three-neck flask with mechanical stirring at 0° C. over 2 h. The     resulting mixture was stirred for additional 1 h at rt. Methyl     2-hydroxycinnamate from Step T8-1 (108 g, 0.61 mol, 1.0 eq),     potassium carbonate (92.2 g, 0.67 mol, 1-0.1 eq), potassium iodide     (20 g, 0.12 mol, 0.2 eq) and DMF (300 mL, spectrometric grade) were     added to the above flask. The reaction mixture was stirred at 70° C.     (external temperature) for 24 h. The reaction was monitored by TLC     (DCM/Et₂O: 95/5). The reaction was allowed to cool to rt and Et₂O     (450 mL) was added. The inorganic salts were removed by filtration     and washed with Et₂O (3×50 mL). The filtrate was diluted with     hexanes (400 mL) and washed with water (3×500 mL), dried over MgSO₄,     filtered and the filtrate evaporated under reduced pressure. The     crude ester (desired product and excess Br—C₂H₄—OTHP) was used for     the subsequent reduction without further purification. -   Step T8-3: DIBAL (1.525 L, 1.525 mol, 2.5 eq, 1.0 M in DCM) was     added slowly to a solution of the above crude ester from Step T8-2     (0.61 mol based on the theoretical yield) in anhydrous DCM (610 mL)     at −35° C. with mechanical stirring over 1.5 h. The resulting     mixture was stirred for 1.5 h at −35° C., then 1.5 h at 0° C. The     reaction was monitored by TLC (hex/EtOAc: 50/50). When complete,     Na₂SO₄.10H₂O (100 g, 0.5 eq) was slowly added; hydrogen evolution     was observed, when it subsided water was added (100 mL). The mixture     was warmed to rt and stirred for 10 min, then warmed to 40° C. with     hot water and stirred under reflux for 20 min. The mixture was     cooled to rt, diluted with DCM (600 mL), and the upper solution     decanted into a filter. The solid that remained in the flask was     washed with dichloromethane (5×500 mL) with mechanical stirring and     filtered. The filtrate from each wash was checked by TLC, and     additional washes performed if necessary to recover additional     product. In an alternative work-up procedure, after dilution with     DCM (600 mL), the mixture was filtered. The resulting solid was then     continuously extracted with 0.5% TEA in dichloromethane using a     Soxhlet extractor. Higher yield was typically obtained by this     alternative procedure, although it does require more time. The     filtrate was concentrated under reduced pressure and the residue     purified by dry pack (EtOAc/hex/Et₃N: 20/80/0.5) to give the product     alcohol as a yellowish oil (yield: 90%). The identity and purity     were confirmed by NMR. -   Step T8-4: To a mixture of the allylic alcohol from Step T8-3 (28 g,     0.100 mol, 1.0 eq) and collidine (0.110 mol, 1.1 eq) in 200 mL of     anhydrous DMF under N₂ was added anhydrous LiCl (4.26 g, 0.100 mol,     1.0 eq.) dissolved in 100 mL of anhydrous DMF. The mixture was then     cooled to 0° C., and MsCl (12.67 g, 0.110 mol, 1.1 eq., freshly     distilled over P₂O₅), was added dropwise. The reaction was allowed     to warm to rt and monitored by TLC (3:7 EtOAc/hex). When the     reaction was complete, NaN₃ (32.7 g, 0.500 mol, 5.0 eq.) was added.     The reaction mixture was stirred at rt O/N with progress followed by     NMR. When the reaction was complete, the mixture is poured into an     ice-cooled water bath, and extracted with diethyl ether (3×). The     combined organic phases were then washed sequentially with citrate     buffer (2×), saturated sodium bicarbonate (2×), and finally with     brine (1×). The organic layer was dried with MgSO₄, filtered and the     filtrate concentrated under reduced pressure. The allylic azide was     obtained in 90% combined yield, and was of sufficient quality to use     as such for the following step. -   Step T8-5: PPh₃ (25.9 g, 0.099 mol, 1.5 eq) was added at 0° C. to a     solution of the allylic azide from Step T8-4 (20.0 g, 0.066 mol, 1.0     eq.) in 100 mL of THF. The solution was stirred for 30 min at 0° C.     and 20 h at rt. Water (12 mL) was then added and the resulting     solution was heated at 60° C. for 4 h. The solution was cooled to     rt, 2N HCl (15 mL) added and the mixture stirred for 90 min at     50° C. The separated organic phase was extracted with 0.05 N HCl     (2×100 mL). The combined aqueous phase was washed with Et₂O (5×150     mL) and toluene (4×150 mL) (more extraction could be necessary,     follow by TLC), which were combined and back-extracted with 0.05 N     HCl (1×100 mL). This acidic aqueous phase from back-extraction was     combined with the main aqueous phase and washed with ether (5×150     mL) again. The pH of the aqueous phase was then adjusted to 8-9 by     the addition of sodium hydroxide (5 N). Care must be exercised to     not adjust the pH above 9 due to the reaction conditions required by     the next step. The aqueous phase was concentrated under reduced     pressure (aspirator, then oil pump) or lyophilized to dryness.     Toluene (2×) was added to the residue and then also evaporated under     reduced pressure to remove traces of water. The crude product     (desired amino alcohol along with inorganic salt) was used for the     next reaction without further purification. -   Step T8-6: A mixture of the crude amino alcohol from Step T8-5 (0.5     mol based on the theoretical yield), Ddz-OPh (174 g, 0.55 mol, 1.1     eq) and Et₃N (70 mL, 0.5 mol, 1.0 eq) in DMF (180 mL) was stirred     for 24 h at 50° C. Additional DMF is added if required to solubilize     all materials. The reaction was monitored by TLC (hex/EtOAc: 50/50,     ninhydrin detection). After the reaction was complete, the reaction     mixture was diluted with Et₂O (1.5 L) and water (300 mL). The     separated aqueous phase was extracted with Et₂O (2×150 mL). The     combined organic phase was washed with water (3×500 mL) and brine     (1×500 mL), dried over MgSO₄, filtered and the filtrate concentrated     under reduced pressure. The layers were monitored by TLC to ensure     no product was lost into the aqueous layer. If so indicated, perform     one or more additional extractions with Et₂O of the aqueous phase to     recover this material. The crude product was purified by dry pack     (recommended column conditions: EtOAc/hex/Et₃N: 35/65/0.5 to     65/35/0.5) to give the tether Ddz-T8 as a pale yellow syrup (yield:     ˜40%). The identity and purity of the product was confirmed by NMR.

¹H NMR (DMSO-d₆): 1.6 ppm (s, 6H, 2×CH₃), 3.6-3.8 ppm (wide s, 10H, 2×OCH₃, 2×OCH₂), 3.95 ppm (triplet, 2H, CH₂N), 6-6.2 ppm (m, 2H, 2×CH), 6.2-6.5 ppm (m, 3H, 3×CH, aromatic), 6.6-7.6 ppm (m, 5H, aromatic).

A standard procedure for the synthesis of tether T9 is shown in FIG. 3.

Tether T9 can also be synthesized from T8 by reduction as in step T9-3 or with other appropriate hydrogenation catalysts known to those in the art.

A standard procedure for the synthesis of Ddz propargylamine is shown in FIG. 4.

In a dried three-neck flask, a solution of propargylamine (53.7 g, 0.975 mol, 1.5 eq) in degassed DMF (Drisolv, 388 mL) was treated with Ddz-N₃ (170.9 g, 0.65 mol, 1.0 eq), tetramethylguanidine (TMG, 81.4 mL, 0.65 mol, 1.0 eq) and DIPEA (113.1 mL, 0.65 mol, 1.0 eq) and stirred at 50° C. O/N. The reaction was monitored by TLC (conditions: 25/75 EtOAc/hex. R_(f): 0.25; detection: UV, ninhydrin). Upon completion, DMF was evaporated under reduced pressure until dryness and the residue dissolved in Et₂O (1 L). The organic solution was washed sequentially with citrate buffer (pH 4.5, 3×), saturated aqueous sodium bicarbonate (2×), and brine (2×), then dried with MgSO₄, filtered and the filtrate evaporated under reduced pressure. A pale orange solid was obtained. This solid was triturated with 1% EtOAc in hex, then collected by filtration and dried under vacuum (oil pump) to provide the desired product (153.4 g, 85.2%).

A standard procedure for the synthesis of tether T10 is shown in FIG. 5A.

Two alternative routes to this tether have been developed. The first synthetic approach proceeded starting from the commercially available monobenzoate of resorcinol (T10-0). Mitsunobu reaction under standard conditions with the protected amino alcohol from Example 9, followed by saponification of the benzoate provided T10-1 in good yield after recrystallization. Alkylation of the phenol with 2-bromoethanol using the optimized conditions shown permitted the desired product Ddz-T10 to be obtained after dry pack purification in 42% yield.

A second synthetic route to T10 is shown in FIG. 5B.

From resorcinol, two successive Mitsunobu reactions are conducted with the appropriate two carbon synthons illustrated, themselves derived from 2-aminoethanol and ethylene glycol, respectively, through known protection methodologies. Lastly, deprotection of the silyl ether, also under standard conditions provided Boc-T10.

Although the yields in the two methods are comparable, the first required less mechanical manipulation and is preferred for larger scales.

A standard procedure for the synthesis of tether T11 is shown in FIG. 6.

A standard procedure for the synthesis of tether T12 is shown in FIG. 7.

In a 3-L flame-dried three-neck flask, a solution of (aminomethyl)phenylthiobenzyl alcohol (12-0, 96 g, 0.39 mol) in degassed DMF (1 L, 0.4 M) was prepared. To this was added DdzN₃ (0.95 eq), followed by TMG (0.39 mol, 49 mL). The reaction was stirred for 10 min, then DIPEA (68 mL, 0.39 mol) added. The mixture was heated at 50° C. under N₂ until TLC indicated no DdzN₃ remained (48 h typically). (TLC eluent: EtOAc:Hex 50:50; detection: ninhydrin). Upon completion, to the reaction mixture was added 3 L citrate buffer and the separated aqueous layer extracted with Et₂O (3×1500 mL). The combined organic phase was washed sequentially with citrate buffer (2×200 mL), water (2×200 mL) and brine (2×200 mL). The organic layer was dried over MgSO₄, filtered and the filtrate evaporated under reduced pressure. A dark orange oil was obtained, which was purified by dry-pack. For this procedure, the oil was first dissolved in EtOAc:Hex:DCM:TEA (20:80:1:0.5, v/v/v/v). At this point, a little extra DCM was sometimes required to ensure complete dissolution. The solution was loaded onto the column, then the column eluted with EtOAc:Hex:DCM:Et₃N (20:80:1:0.5) until all the impurities were separated out as indicated by TLC, paying particular attention to that closest to the desired product. The elution was then continued with EtOAc:Hex:Et₃N 30:70:0.5 (v/v/v) and finally with EtOAc:hexanes:Et₃N (50:50:0.5) to elute the desired product. After removal of the solvent from the fractions containing the product under reduced pressure, the residue was dissolved in the minimum amount of DCM, a three-fold larger volume of hexanes added, then the solvents again evaporated under reduced pressure. This treatment was repeated until an off-white foam was obtained. The latter solidified while drying under vacuum (oil pump). Alternatively, the material yielded a solid after sequential concentration with DCM (1×) and hexanes (2×). Tether Ddz-T12 was obtained as an off-white solid (85-90% yield).

Example 29 Standard Procedure for Attachment of Tethers Utilizing the Mitsunobu Reaction Example 29-A Using PPh₃-DIAD Isolated Adduct

To a 0.2 M solution of the appropriate tether (1.5 eq) in THF or THF-toluene (1:1) was added the PPh₃-DIAD (pre-formed by mixing equivalent amounts of the reagents and isolated by evaporation of solvent, see Example 29-C) adduct (1.0 eq.). The resultant mixture was manually agitated for 10 sec (the solution remained turbid), then added to the resin. Alternatively, the resin was added to the solution. The reaction suspension was agitated O/N (after ˜5 min the mixture becomes limpid). The resin was filtered and washed 2×DCM, 1× toluene, 1×EtOH, 1× toluene, 1×(DCM/MeOH), 1×(THF/MeOH), 1×(DCM/MeOH), 1×(THF/MeOH), 2×DCM, then dried in the standard manner.

Example 29-B Using “PPh₃-DIAD In Situ Procedure”

To a 0.2 M solution of the appropriate tether (4 eq) in THF or THF-toluene (1:1) was added triphenylphosphine (4 eq). The resultant mixture was manually shaken until a homogenous solution was obtained, then added to the resin. Alternatively, the resin (or IRORI™ MiniKans® (NEXUS Biosystems, Poway, Calif.), miniaturized microreactors, containing resin) was added to the solution. To this suspension was then added DIAD (3.9 eq) and the reaction agitated O/N. Note: Since the reaction is exothermic, for larger scales, the reaction should be cooled in an ice bath. In addition, an appropriate vent must be supplied to allow any pressure build-up to be released. The resin was filtered and washed DCM (2×), toluene (1×), EtOH (1×), toluene (1×), DCM/MeOH (1×), 1×THF/MeOH (1×), DCM/MeOH (1×), THF/MeOH (1×), 2×DCM, then dried in the standard manner.

A procedure for the synthesis of PPh₃-DIAD adduct is shown in FIG. 8.

DIAD (1 eq) was added dropwise to a well-stirred solution of triphenylphosphine (1 eq) in THF (0.4 M) at 0° C. under nitrogen. The mixture was then maintained at 0° C. with stirring for 30 min. The white solid obtained was collected by filtration (use medium sized fritted filters), washed with cold anhydrous THF until the washes were colorless, and lastly washed once with anhydrous Et₂O. The white solid product was then vacuum-dried (oil pump) and stored under nitrogen. (Note: The PPh₃-DIAD adduct can be made in larger than immediately required quantity and stored under nitrogen; it is very important to store this reagent under anhydrous conditions.)

Example 30 Standard Procedure for Attachment of Tethers via Reductive Amination as Shown in FIG. 9

In certain instances, the Mitsunobu process of Example 29 cannot be applied or is not efficient for incorporation of the tether. Hence, reductive amination has been developed as an alternative that can be employed for tether incorporation as illustrated hereinbelow for one of the preferred tethers. Similar chemistry can be used to incorporate other tethers of the present invention.

The Tether (30-2) with the amine protected as its Ddz derivative was efficiently oxidized to the corresponding aldehyde 30-2 using SO₃.pyr in DMSO-Et₃N-DCM. This aldehyde (0.14 mmol, 56 mg, 1.5 eq based upon loading of resin support) was dissolved in a 1:3 mixture of TMOF-MeOH (DriSolv, 4 mL) at rt. To this was added the resin containing the tripeptide (30-1, as its trifluoroacetic acid salt from the deprotection of the terminal amine), the mixture was agitated briefly to wet the resin, and then borane-pyridine complex (as the commercially available 8 M solution, 23 μL, 2 eq) was introduced to the suspension. The reaction was agitated O/N, then the resin filtered, washed with DCM (2×), THF (1×), DCM/MeOH [3:1] (1×), THF/MeOH [3:1] (1×), DCM (2×) and dried in the standard manner. Care must be taken to ensure that the desired resin bound product 30-3 is not contaminated with the dialkylated material. However, even if the reaction does not proceed to completion or if a small amount of the dialkylation side product is present, the material is of sufficient purity for the macrocyclization reaction.

A standard procedure for the synthesis of tether T28 is shown in FIG. 10. Henry reaction of 2-hydroxybenzaldehyde 28-0 provided 28-1 in 79% yield. This was followed by reduction first with sodium borohydride, then with catalytic hydrogenation, to give the amine, which was then protected as its Boc derivative, 28-2. Yields of these first two steps were lower on larger scales. Alkylation of 28-2 with the TBDMS ether of 2-bromoethanol, itself synthesized by standard methods, gave 28-3 in 74% yield. Deprotection of the silyl ether under standard conditions yielded the desired protected tether, Boc-T28. Alternative use of ethylene carbonate for the phenol alkylation to avoid the protection/deprotection steps, gave 73% yield.

A standard procedure for the synthesis of tether T32 is shown in FIG. 11.

A standard procedure for the synthesis of tether T33a and T33b is shown in FIGS. 12A and 12B.

The construction to the (R)-isomer of this tether (T33a) was accomplished from 2-iodophenol (33-0) and (S)-methyl lactate (33-A). Mitsunobu reaction of 33-0 and 33-A proceeded with inversion of configuration in excellent yield to give 33-1. Reduction of the ester to the corresponding alcohol (33-2) also occurred in high yield and was followed by Sonagashira reaction with Ddz-propargylamine. The alkyne in the resulting coupling product, 33-3, was reduced with catalytic hydrogenation. Workup with scavenger resin provided the desired product, Ddz-T33a.

The synthesis of the (S)-enantiomer (Ddz-T33b) was carried out in an identical manner in comparable yield starting from (R)-methyl lactate (33-B). See FIG. 12B.

Standard procedures for the synthesis of various tethers are shown in the figures: tether T34 (FIG. 13), tether T35 (FIG. 14), tether T36 (FIG. 15), tether T37 (FIG. 16), tether T38 (FIG. 17), tether T39 (FIG. 18), tether T40 (FIG. 19), tether T41 (FIG. 20) and tether T42 (FIG. 21).

E. Examples of Synthetic Strategies for the Macrocyclic Compounds of the Invention

FIG. 22 presents a scheme depicting a thioester strategy for macrocyclic compounds of the present invention.

It should be noted that one or more of the amino acids indicated can be replaced by corresponding hydroxy acids and coupled to the next building block utilizing methods known to those in the art.

Example 47 Standard Procedure for Macrocyclization with Thioester Linker

The resin containing the cyclization precursor is combined in an appropriate vessel with pre-washed MP-carbonate resin [Argonaut Technologies, Foster City, Calif., commercially supplied MP-carbonate resin was treated with 3×THF (1 L per 400 g) and dried O/N at 30° C. in a vacuum oven] (1.4 to 1.6 eq relative to the initial loading of the synthesis resin). A 0.2 M DIPEA solution in THF was then added to the combined resins (1 mL/60 mg MP-carbonate resin) and the suspension agitated O/N at rt. Subsequently, the resin was filtered and rinsed 2×THF. The combined filtrates are collected together in an appropriate vessel, then the volatile contents evaporated under reduced pressure [in addition to the standard methods, solvent can also be removed in vacuo using centrifugal evaporation (ThermoSavant Discovery®, SpeedVac® or comparable) (Thermo Electron Corporation, Waltham, Mass.)] to provide the crude macrocycles.

Example 48 Standard Procedure for Silver-Assisted Macrocyclization with Thioester Linker

Except for the cyclization itself and subsequent work-up, this procedure is identical to that of Example 47. The resin containing the cyclization precursor was combined in an appropriate vessel with pre-washed MP-carbonate resin [Argonaut Technologies, commercially supplied MP-carbonate resin was treated with THF (3×, 1 L per 400 g) and dried O/N at 30° C. in a vacuum oven] (1.4 to 1.6 eq relative to the initial loading of the synthesis resin). To this was added THF (1 mL per 100 mg resin) and silver trifluoroacetate (1 eq relative to the initial loading of the resin). Finally, an amount of DIPEA sufficient to obtain a 0.2 M solution was added. The reaction mixture was agitated at rt O/N. The solution was then filtered and the resins washed 2×THF. The filtrates are collected together in an appropriate vessel, then evaporated under reduced pressure [(the volatile contents could also be removed in vacuo using centrifugal evaporation (ThermoSavant Discovery®, SpeedVac® or comparable)] to provide the crude macrocycles. For this procedure, silver trifluoroacetate should be stored in a dessicator between uses. In addition, it is recommended to use a new bottle of THF (or a bottle that has been recently opened under N₂ or Ar) to minimize formation of silver oxide.

Additionally, a ring-closing metathesis (RCM) strategy, as developed by Grubbs et al. can also be used to access some of the macrocyclic compounds of the invention (see for example U.S. Pat. No. 5,811,515; Grubbs, R. H. et al. J. Org. Chem. 2001, 66, 5291-5300; Fürstner, A. Angew. Chem. Int. Ed. 2000, 39, 3012-3043).

To access certain derivatives of compounds of the present invention, additional reactions from those in the general scheme were required. For some, it was advantageous to react the functionality to be derivatized prior to the formation of the macrocyclic ring. The cyclic structure can restrict access of reagents to that functionality. For example, in the synthesis of N-methyl and N-acyl derivatives of macrocycles, where the secondary nitrogen atom of the ring is the site of derivatization, the reaction is preferred to be performed prior to the application of the appropriate cyclization protocol.

In other cases, for example the derivatization of side chain functionality, the reaction was best performed after formation of the macrocyclic ring. For example, further reaction of amino moieties on side chains examples was typically efficiently done by reaction of the partially protected macrocycle. In this manner, acylation, sulfonylation, alkylation (via reductive amination), guanidine and urea formation were performed via standard methods.

Table 1, hereinbelow, shows a representative, but by no means exclusive, summary of the chemical synthesis of several representative compounds of the invention.

TABLE 1 Synthesis of Representative Compounds of the Present Invention Tether Additional AA₁ AA₂ AA₃ Tether Attachment Steps 1 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T8 Example 29 none 2 Bts-D-Phe Boc-D-Val Boc-Nva Boc-T8 Example 29 none 3 Bts-D-Phe Boc-D-Val Boc-Nva Boc-T9 Example 29 none 4 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T9 Example 29 none 5 Bts-D-Tyr(tBu) Boc-D-Ala Boc-Nva Ddz-T8 Example 29 none 6 Bts-D-Tyr(tBu) Boc-D-Val Boc-Met Ddz-T8 Example 29 none 7 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nle Ddz-T8 Example 29 none 8 Bts-D-Tyr(tBu) Boc-D-Val Boc-Phe Ddz-T8 Example 29 none 9 Bts-D-Tyr(tBu) Boc-D-Val Boc-Val Ddz-T8 Example 29 none 10 Bts-D-Tyr(tBu) Boc-D-Val Boc-Leu Ddz-T9 Example 29 none 11 Bts-D-2-Nal Boc-D-Val Boc-Nva Boc-T8 Example 29 none 12 Bts-D-Tyr(tBu) Boc-D-Val Boc-Abu Ddz-T8 Example 29 none 13 Bts-D-Phe Boc-D-Val Boc-Leu Boc-T9 Example 29 none 14 Bts-D-2-Nal Boc-D-Val Boc-Leu Boc-T9 Example 29 none 15 Bts-D-Phe(3Cl) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 16 Bts-D-Phe(4Cl) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 17 Bts-D-Trp(Boc) Boc-D-Val Boc-Nva Ddz-T9 Example 29 none 18 Bts-D-Tyr(tBu) Boc-D-2-Abu Boc-Nva Ddz-T9 Example 29 none 19 Bts-D-Phe(4F) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 20 Bts-D-Phe Boc-D-Val Boc-Leu Boc-T8 Example 29 none 21 Bts-D-2-Nal Boc-D-Val Boc-Leu Boc-T8 Example 29 none 22 Bts-D-Tyr(OMe) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 23 Bts-D-1-Nal Boc-D-Val Boc-Nva Boc-T9 Example 29 none 24 Bts-D-2-Thi Boc-D-Val Boc-Nva Boc-T9 Example 29 none 25 Bts-D-Phe(2Cl) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 26 Bts-D-Tyr(tBu) Boc-D-Val Boc-Cpa Ddz-T9 Example 29 none 27 Bts-D-4-Thz Boc-D-Val Boc-Nva Boc-T9 Example 29 none 28 Bts-D-3-Pal Boc-D-Val Boc-Nva Boc-T9 Example 29 none 29 Bts-D-Tyr(tBu) Boc-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 none 30 Bts-D-Tyr(tBu) Hnva(THP) Boc-Nva Ddz-T9 Example 29 none 34 Bts-D-Tyr(tBu) Ddz-D-Tyr(tBu) Boc-Nva Ddz-T8 Example 29 None 38 Bts-D-Tyr(tBu) Boc-D-Val Boc-Ala Ddz-T8 Example 29 none 39 Bts-D-Tyr(tBu) Boc-D-Val Boc-□-Ala Ddz-T8 Example 29 none 40 Bts-D-Tyr(tBu) Boc-D-Val Boc-Gly Ddz-T8 Example 29 none 41 Bts-D-Tyr(tBu) Boc-DPhe Boc-Nva Ddz-T8 Example 29 none 52 Bts-D-Tyr(tBu) Boc-D-Val Boc-Phg Ddz-T8 Example 29 none 55 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Lys(Boc) Ddz-T8 Example 29 none 56 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Orn(Boc) Ddz-T8 Example 29 none 57 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Ser(tBu) Ddz-T8 Example 29 none 58 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Tyr(tBu) Ddz-T8 Example 29 none 59 Bts-D-Tyr(tBu) Ddz--D-Val Ddz-Trp(Boc) Ddz-T8 Example 29 none 60 Bts-D-Tyr(tBu) Boc-D-Val Boc-Tyr(OMe) Ddz-T8 Example 29 none 65 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T2 Example 29 none 71 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T10 Example 29 none 72 Bts-D-Tyr(tBu) Boc-D-Val Boc-2-Nal Ddz-T8 Example 29 none 76 Bts-D-Tyr(tBu) Boc-D-2-Nal Boc-Nva Ddz-T8 Example 29 none 77 Bts-D-Tyr(tBu) Boc-D-Nle Boc-Nva Ddz-T8 Example 29 none 80 Bts-D-Tyr(tBu) Boc-D-Val Boc-Ile Ddz-T8 Example 29 none 85 Bts-D-Tyr(tBu) Boc-D-Val Boc-D-Nva Ddz-T8 Example 29 none 87 Bts-D-Bip Boc-D-Val Boc-Nva Boc-T9 Example 29 none 88 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T9 Example 29 none 89 Bts-D-Hfe Boc-D-Val Boc-Nva Boc-T9 Example 29 none 90 Bts-D-Dip Boc-D-Val Boc-Nva Boc-T9 Example 29 none 91 Bts-D-Tyr(tBu) Boc-D-Nva Boc-Nva Ddz-T9 Example 29 none 92 Bts-D-Tyr(tBu) Boc-D-Tle Boc-Nva Ddz-T9 Example 29 none 96 Bts-D-Tyr(tBu) Boc-β-Ala Boc-Nva Ddz-T9 Example 29 none 97 Bts-D-Tyr(tBu) Boc-D-Chg Boc-Nva Ddz-T9 Example 29 none 98 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T18 Example 29 none 99 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T15 Example 29 none 109 Bts-D-Tyr(tBu) Boc-D-Val Ddz-Dab(Boc) Ddz-T9 Example 29 none 110 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T11 Example 29 none 111 Bts-D-Tyr(tBu) Boc-D-Val Hval(THP) Ddz-T9 Example 29 none 112 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ddz-T9 Example 29 none 120 Bts-D-Tyr(tBu) Boc-D-Pro Boc-Nva Ddz-T8 Example 29 none 121 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Ac-T8-NH2 Example 29 none 122 Boc-D-3-Pal Boc-D-Val Boc-Nva Boc-T9 Example 30 none 123 Boc-D-2-Pal Boc-D-Val Boc-Nva Boc-T9 Example 30 none 124 Boc-D-4-Pal Boc-D-Val Boc-Nva Boc-T9 Example 30 none 125 Bts-D-Tyr(tBu) Boc-D-Cpg Boc-Nva Boc-T9 Example 29 none 126 Bts-D-Tyr(tBu) Boc-D-Val Boc-NMeLeu Boc-T9 Example 29 none 127 Boc-D-His(Mts) Boc-D-Val Boc-Nva Boc-T12 Example 30 none 128 Bts-D-Tyr(OMe) Boc-D-Val Boc-Leu Boc-T9 Example 29 none 129 Bts-D-1-Nal Boc-D-Val Boc-Leu Boc-T9 Example 29 none 130 Bts-D-2-Thi Boc-D-Val Boc-Leu Boc-T9 Example 29 none 131 Bts-D-Phe(3Cl) Boc-D-Val Boc-Leu Boc-T9 Example 29 none 132 Bts-D-Phe(4Cl) Boc-D-Val Boc-Leu Boc-T9 Example 29 none 133 Bts-D-Phe(4F) Boc-D-Val Boc-Leu Boc-T9 Example 29 none 134 Bts-D-Phe(3Cl) Boc-D-Val Boc-Leu Boc-T2 Example 29 none 135 Bts-D-Tyr(OMe) Boc-D-Val Boc-Leu Boc-T11 Example 29 none 136 Bts-D-1Nal Boc-D-Val Boc-Leu Boc-T11 Example 29 none 137 Bts-D-2-Thi Boc-D-Val Boc-Leu Boc-T11 Example 29 none 138 Bts-D-Phe(3Cl) Boc-D-Val Boc-Leu Boc-T11 Example 29 none 139 Bts-D-Phe(4Cl) Boc-D-Val Boc-Leu Boc-T11 Example 29 none 140 Bts-D-Phe(4F) Boc-D-Val Boc-Leu Boc-T11 Example 29 none 141 Bts-D-Tyr(OMe) Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 142 Bts-D-1-Nal Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 143 Bts-D-2-Thi Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 144 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 145 Bts-D-Phe(4Cl) Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 146 Bts-D-Phe(4F) Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 147 Bts-D-Tyr(OMe) Boc-D-Val Boc-Cpa Boc-T11 Example 29 none 148 Bts-D-1-Nal Boc-D-Val Boc-Cpa Boc-T11 Example 29 none 149 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T11 Example 29 none 150 Bts-D-Phe(4Cl) Boc-D-Val Boc-Cpa Boc-T11 Example 29 none 151 Bts-D-Phe(4F) Boc-D-Val Boc-Cpa Boc-T11 Example 29 none 152 Bts-D-Tyr(OMe) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 none 153 Bts-D-1-Nal Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 none 154 Bts-D-2-Thi Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 none 155 Bts-D-Phe(3Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 none 156 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 none 157 Bts-D-Phe(4F) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 none 158 Bts-D-Phe(3Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T11 Example 29 none 159 Bts-D-Tyr(But) Boc-D-Ile Boc-Nva Boc-T9 Example 29 none 160 Bts-D-Tyr(But) Boc-D-allolle Boc-Nva Boc-T9 Example 29 none 161 Boc-D-Phe(4CH2NHFmoc) Boc-D-Val Boc-Nva Boc-T9 Example 30 none 162 Bts-D-Phe(2Me) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 163 Bts-D-Phe(3Me) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 164 Bts-D-Phe(4Me) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 165 Bts-D-Phe(3OMe) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 166 Bts-D-Phe(2OMe) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 167 Bts-D-3- Boc-D-Val Boc-Nva Boc-T9 Example 29 none benzothienyl 168 Bts-D-3-Thi Boc-D-Val Boc-Nva Boc-T9 Example 29 none 169 Bts-D-□-HomoPhe(3Cl) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 170 Bts-D-Phe(3,4diCl) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 171 Bts-D-Phe(3,4diF) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 172 Bts-D-Phe(3,4diOMe) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 173 Bts-D-1Nal Hnva(THP) Boc-Nva Boc-T9 Example 29 none 174 Bts-D-Tyr(OMe) Hnva(THP) Boc-Nva Boc-T9 Example 29 none 175 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Boc-T33b Example 29 none 176 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Boc-T33a Example 29 none 177 Bts-D-Tyr(tBu) Boc-D-Val Boc-Nva Boc-T28 Example 29 none 178 Bts-D-Tyr(OMe) Ddz-D-Val Ddz-Ser(tBu) Ddz-T9 Example 29 none 179 Bts-D-1-Nal Ddz-D-Val Ddz-Ser(tBu) Ddz-T9 Example 29 none 180 Bts-D-2-Thi Ddz-D-Val Ddz-Ser(tBu) Ddz-T9 Example 29 none 181 Bts-D-Phe(3Cl) Ddz-D-Val Ddz-Ser(tBu) Ddz-T9 Example 29 none 182 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Ser(tBu) Ddz-T9 Example 29 none 183 Bts-D-Phe(4F) Ddz-D-Val Ddz-Ser(tBu) Ddz-T9 Example 29 none 184 Bts-D-1-Nal Ddz-D-Val Ddz-Dap(Boc) Ddz-T11 Example 29 none 185 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T11 Example 29 none 186 Ddz-D-Tyr(tBu) Ddz-D-Val Ddz-His(Mts) Ddz-T9 Example 30 none 187 Bts-D-Phe(3CF3) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 188 Bts-D-Phe(3F) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 189 Bts-D-Phe(4NO2) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 190 Bts-D-3-benzothienyl Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 191 Bts-D-Phe(3OMe) Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 192 Bts-D-Phe(3,4diCl) Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 193 Bts-D-Phe(3,4diF) Boc-D-Val Boc-Cpa Boc-T9 Example 29 none 194 Bts-D-Tyr(OMe) Boc-D-Val Boc-Nva Boc-T34 Example 29 none 195 Bts-D-Tyr(OMe) Boc-D-Val Boc-Nva Boc-T38 Example 29 none 196 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Ddz-T32(Boc) Example 29 none 197 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T34 Example 29 none 198 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T38 Example 29 none 199 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T41 Example 29 none 200 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T8 Example 29 none 201 Bts-D-1-Nal Boc-D-Val Boc-Nva Boc-T8 Example 29 none 202 Bts-D-Phe(3OMe) Boc-D-Val Boc-Nva Boc-T8 Example 29 none 203 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 acetylation 204 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 guanidinylation 205 Bts-D-Phe(3Cl) Boc-D-Val Boc-NMeLeu Boc-T9 Example 29 none 206 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 mesylation 207 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 TMS- isocyanate followed by dilute acid 208 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 guanidinylation 209 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 acetylation 210 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 reductive amination with acetone 211 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 reductive amination with excess formaldehyde 212 Bts-D-Phe(4Cl) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 reductive amination with acetone 213 Bts-D-Tyr(3,5dil) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 214 Bts-D-Tyr(OMe) Boc-D-Val Boc-Hse(Bzl) Boc-T9 Example 29 hydrogenolysis for protecting group removal 215 Bts-D-Tyr(tBu) Ddz-D-Val Ddz-Dap(Boc) Ddz-T9 Example 29 reductive amination with excess formaldehyde 216 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T40 Example 29 none 217 Bts-D-Phe(3Cl) Boc-D-Val Boc-Cpa Boc-T36 Example 29 none 218 Bts-D-Phe(3Cl) Boc-D-Val Boc-Nva Boc-T39 Example 29 none 219 Bts-D-Phe(3Cl) Boc-D-Val Boc-Nva Boc-T37 Example 29 none 220 Bts-D-Phe(3Cl) Boc-D-Val Boc-Nva Boc-T39 Example 29 none 221 Bts-D-Phe(3Cl) Boc-D-Val Boc-Nva Boc-T35 Example 29 none 222 Bts-D-Tyr(3tBu) Boc-D-Val Boc-Nva Boc-T9 Example 29 none 223 Bts-D-Tyr(But) Boc-D-Val Boc-Nva Boc-T9 Example 29 acetylation 224 Bts-D-1-Nal Boc-D-Val Boc-Leu Boc-T9 Example 29 reductive amination with formaldehyde 225 Bts-D-1-Nal Boc-D-Val Boc-Leu Boc-T9 Example 29 acetylation 226 Bts-D-1-Nal Boc-D-Val Boc-Leu Boc-T9 Example 29 reductive amination with aldehyde 227 Bts-D-1-Nal Boc-D-Val Boc-Leu Boc-T9 Example 29 reductive amination with benzaldehyde Notes Any amino acid or tether designated as the Boc derivative could be substituted with the corresponding Ddz derivative.

D. Analytical Data for Selected Compounds of the Invention

¹H and ¹³C NMR spectra were recorded on a Varian Mercury 300 MHz spectrometer (Varian, Inc., Palo Alto, Calif.) and are referenced internally with respect to the residual proton signals of the solvent. Information about the conformation of the molecules in solution can be determined utilizing appropriate two-dimensional NMR techniques known to those skilled in the art. HPLC purifications were run on a Waters Xterra® MS C18 column, using the Waters FractionLynx® system (Waters Corporation, Milford, Mass.). Automated medium pressure chromatographic purifications were performed on an Isco CombiFlash® 16× system with disposable silica or C18 cartridges that permitted up to sixteen (16) samples to be run simultaneously (Teledyne Isco, Inc., Lincoln, Nebr.). MS spectra were recorded on a Waters Micromass® Platform II or ZQ™ system. HRMS spectra were recorded with a VG Micromass ZAB-ZF spectrometer. Chemical and biological information were stored and analyzed utilizing the ActivityBase® database software (ID Business Solutions Ltd., Guildford, Surrey, UK).

General Methods for Analytical HPLC Analyses

HPLC analyses are performed on a Waters Alliance® system 2695 running at 1 mL/min using an Xterra MS C18 column 4.6×50 mm (3.5 μm). A Waters 996 PDA provided UV data for purity assessment (Waters Corporation, Milford, Mass.). An LCPackings (Dionex Corporation, Sunnyvale, Calif.) splitter (50:40:10) allowed the flow to be separated in three parts. The first part (50%) went to a Micromass® Platform II MS equipped with an APCI probe for identity confirmation. The second part (40%) went to an evaporative light scattering detector (ELSD, Polymer Laboratories, now part of Varian, Inc., Palo Alto, Calif., PL-ELS-1000™) for purity assessment and the last portion (10%) to a chemiluminescence nitrogen detector (CLND, Antek® Model 8060, Antek Instruments, Houston, Tex., part of Roper Industries, Inc., Duluth, Ga.) for quantitation and purity assessment. Data was captured and processed utilizing the most recent version of the Waters Millenium® software package (Milford, Mass.).

An example LC method suitable for compounds of the present invention uses MeOH as solvent A, H₂O as solvent B and 1% TFA/H₂O as solvent D. Initial mobile-phase composition is 5% A, 85% B and 10% D. Details of the standard gradient method are shown below:

Time A % B % D % Curve 0.00 5 85 10 6 1.00 5 85 10 6 6.00 50 40 10 6 9.00 50 40 10 6 14.00 90 0 10 6 17.00 90 0 10 6 17.50 5 85 10 6 20.00 5 85 10 6

Compounds 2-6, 8-10, 56, 65 and 144 are as defined in Table (3), hereinbelow.

Compound 2

Yield: 12 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 8.83 (m, 1H); 8.53 (m, 1H); 7.63 (m, 1H); 7.4-7.08 (m, 7H); 7.00-6.84 (m, 2H); 6.60 (d, 15 Hz, 1H); 6.41 (dt, 15 Hz, 5.4 Hz, 1H); 4.35 (m, 1H); 4.25-4.05 (m, 3H); 3.94 (dt, 1H, 6 Hz, 15 Hz); 3.79 (dd, 1H, 3.6 Hz, 8.4 Hz); 3.60 (m, 1H); 3.52-3.40 (bd, 1H); 3.22-3.06 (m, 4H); 1.88 (m, 2H); 1.54-1.28 (m, 2H); 1.25 (d, 3H, 4.8 Hz); 1.22 (d, 3H, 2.7 Hz); 0.92-0.80 (m, 6H).

HRMS calc. for C₃₀H₄₀N₄O₄: 520.3049; found 520.3057±0.0016

HPLC [standard gradient method (refers to that presented in General Methods for Analytical HPLC Analyses)] t_(R)=9.55 min.

Compound 4

Yield: 12 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.35 (b, 1H); 8.98 (b, 1H); 5.52 (d, 1H, 8.4 Hz); 8.38 (b, 1H); 7.25 (b, 1H); 7.13-7.07 (m, 4H); 6.86 (t, 2H, 7.5 Hz); 6.57 (d, 2H, 8.7 Hz); 4.33 (b, 1H); 4.21-4.02 (m, 3H); 3.78 (dd, 1H, 3.3 Hz; 8.1 Hz); 3.65-3.54 (m, 1H); 3.31-3.23 (m, 1H); 3.13-3.02 (m, 4H); 2.78-2.2.28-2.18 (m, 1H); 2.0-1.80 (m, 2H); 1.50-1.30 (m, 3H); 1.25 (d, 3H, 4.5 Hz); 1.22 (d, 3H, 4.5 Hz); 1.01 (d, 3H, 6.6 Hz); 0.90 (d, 3H, 6.6 Hz); (t, 3H, 7.5 Hz).

¹³C NMR (75.5 MHz, DMSO-d₆) δ 172.22; 171.37; 157.77; 157.44; 156.04; 131.76; 130.80; 130.70; 127.88; 121.82; 115.83; 111.71; 62.13; 60.62; 54.21; 52.81; 47.13; 42.47; 33.31; 29.69; 29.30; 28.61; 20.36; 19.44; 18.72; 17.60; 13.97.

HRMS calc. for C₃₀H₄₂N₄O₅: 538.3155; found: 538.3145±0.0016

HPLC (standard gradient) t_(R)=8.12 min.

Compound 5

Yield: 17 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.02 (b, 1H); 8.47 (d, 1H, 8.4 Hz); 7.7 (b, 1H); 7.58 (d, 1H, 5.4 Hz); 7.28 (dd, 1H, 7.8 Hz, 0.8 Hz); 7.20 (t, 1H, 9.0 Hz, 0.8 Hz); 7.14 (d, 2H, 8.4 Hz); 6.98-6.91 (m, 3H); 6.66 (d, 8.7 Hz); 6.63 (d, 1H, 15.0 Hz); 6.43 (dt, 1H, 6.0 Hz, 15.0 Hz); 4.28-3.86 (m, 6H); 3.60-3.40 (m, 2H); 3.22-3.12 (m, 1H0; 3.05 (d, 2H, 5.4 Hz); 1.92-1.80 (m, 1H); 1.56-1.40 (m, 1H); 1.36-1.20 (m, 2H); 1.25 (d, 3H, 6.6 Hz); 0.84 (t, 3H, 7.2 Hz).

¹³C NMR (75.5 MHz, DMSO-d₆) δ 172.54; 171.86; 158.97; 158.56; 127.39; 155.84; 131.62; 129.73; 129.20; 129.02; 128.43; 126.30; 124.51; 122.01; 115.85; 112.88; 61.23; 52.90; 51.23; 47.08; 42.66; 36.13; 33.30; 21.14; 19.57; 17.07; 14.14; 11.49.

HRMS calc. for C₂₈H₃₆N₄O₅: 508.2685; found: 508.2681±0.0015

HPLC (standard gradient) t_(R)=7.67 min.

Compound 6

Yield: 16 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.37 (b, 1H); 8.87 (b, 1H); 8.61 (d, 1H, 8.7 Hz); 7.62 (b, 1H); 7.27 (d, 1H, 7.8 Hz); 7.21 (t, 1H, 8.4 Hz); 7.14 (d, 2H, 8.4 Hz); 6.98-6.87 (m, 3H); 6.64 (d, 2H, 8.1 Hz); 6.70 (d, 1H, 15.6 Hz); 6.39 (dt, 1H, 6.3 Hz, 15.6 Hz); 4.44-4.36 (m, 1H); 4.34-4.08 (m, 2 Hz); 4.45-3.92 (dt, 1H, 6.9 Hz, 15.6 Hz); 3.74 (dd, 1H, 3.6 Hz, 8.4 Hz); 3.54-3.26 (m, 3H); 3.22-3.02 (m, 3H); 2.60-2.36 (m, 4H); 2.24-2.14 (m, 1H); 2.02 (s, 3H); 1.96-1.89 (m, 1H); 1.80-1.66 (m, 1H); 1.01 (d, 3H, 6.3 Hz); 0.90 (d, 3H, 6.6 Hz).

¹³C NMR (75.5 MHz, DMSO-d₆) δ 171.51; 171.26; 158.90; 158.49; 157.38; 155.86; 131.63; 129.82; 129.21; 128.86; 128.63; 126.21; 121.98; 115.83; 112.83; 62.11; 61.06; 51.97; 47.10; 42.78; 30.91; 30.67; 29.34; 20.37; 19.39; 15.06.

HRMS calc. for C₃₀H₄₀N₄O₅S: 568.2719; found: 568.2711±0.0017

HPLC R_(t) (general method) 7.92 min.

Compound 8

Yield: 27 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.05 (b, 1H); 8.43 (b, 1H); 8.34 (d, 1H, 9.3 Hz); 7.40 (b, 1H); 6.97 (d, 1H, 7.5 Hz); 6.92-6.74 (m, 9H); 6.67-6.54 (m, 2H); 6.33-6.25 (m, 3H); 6.10 (dt, 1H, 5.7 Hz, 16.2 Hz); 4.22 (dt, 1H, 0.9 Hz, 12 Hz); 3.94-6.66 (m, 4H); 3.30 (dd, 1H, 3.6 Hz, 7.8 Hz); 3.24 (m, 1H); 3.18 (m, 1H); 2.85-2.68 (m, 3H); 2.44-2.23 (m, 2H); 1.32 (o, 1H, 7.5 Hz); 0.97-0.89 (m, 1H); 0.42 (d, 3H, 6.6 Hz); 0.01 (d, 3H, 6.6 Hz).

¹³C NMR (75.5 MHz, DMSO-d₆) δ 171.20; 157.35; 155.88; 139.12; 131.61; 130.87; 129.74; 129.21; 128.77; 128.88; 126.85; 126.19; 121.97; 115.82; 112.84; 62.04; 61.10; 55.07; 50.01; 47.09; 42.85; 37.42; 29.11.

HRMS calc. For C₃₄H₄₂N₄O₅: 586.3155; found: 586.3145±0.0017

HPLC R_(t) (general method) 9.34 min.

Compound 9

Yield: 17 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.39 (b, 1H); 8.83 (b, 1H); 8.29 (d, 1H, 9.3 Hz); 7.62 (b, 1H); 7.28 (d, 1H, 6.6 Hz); 7.20 (t, 1H, 6.9 Hz); 7.12 (d, 2H, 7.8 Hz); 6.98-6.91 (m, 2H); 6.63 (d, 2H, 8.4 Hz); 6.58 (d, 1H, 16.2 Hz); 6.40 (dt, 1H, 5.7 Hz, 16.2 Hz); 4.29-4.13 (m, 3H); 4.03-3.92 (m, 2H); 3.52 (m, 1H); 3.15-3.05 (m, 3H); 2.45-2.37 (m, 1H); 1.96-1.88 (m, 1H); 1.25 (dd, 2H, 4.5 Hz; 6 Hz); 1.01 (d, 3H, 6.3 Hz); 0.91 (d, 3H, 6.6 Hz); 0.86 (d, 3H, 7.2 Hz); 0.81 (d, 3H, 6.6 Hz).

¹³C NMR (75.5 MHz, DMSO-d₆) δ 171.85; 171.17; 157.37; 155.87; 131.59; 129.88; 129.18; 128.97; 128.78; 128.51; 126.16; 121.97; 115.83; 112.85; 61.55; 61.18; 58.15; 54.22; 47.08; 42.89; 36.32; 29.35; 29.00; 20.34; 19.56; 18.73; 17.44.

HRMS calc. for C₃₀H₄₀N₄O₅ 536.2998; found: 536.2990±0.0017.

HPLC (standard gradient) t_(R)=8.15 min.

Compound 10

Yield: 24 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.33 (b, 1H); 8.82 (b, 1H); 8.56 (d, 1H, 8.3 Hz); 7.60 (b, 1H); 7.27 (d, 2H, 7.8 Hz); 7.20 (t, 1H, 7.8 Hz); 7.13 (d, 2H, 8.4 Hz); 6.95 (t, 2H, 7.8 Hz); 6.64 (d, 2H, 8.4 Hz); 6.57 (d, 1H, 15.4 Hz); 6.38 (dt, 1H, 15.4 Hz, 5.8 Hz); 4.26-4.10 (m, 3H); 3.96 (dt, 1H, 5.4 Hz, 8.4 Hz); 3.77 (dd, 1H, 3.7 Hz, 7.8 Hz); 3.51-3.24 (m, 3H); 3.18-3.02 (m, 3H); 1.90 (h, 1H, 6.4 Hz); 1.73-1.54 (m, 2H); 1.45 (dt, 1H, 6.7 Hz, 0.9 Hz); 0.99 (d, 3H, 6.6 Hz); 0.89 (d, 3H, 6.3 Hz); 0.87 (d, 3H, 6.0 Hz); 0.80 (d, 3H, 6.3 Hz).

¹³C NMR (75.5 MHz, DMSO-d₆) δ 172.23; 171.17; 157.37; 155.88; 131.62; 129.82; 129.19; 128.95; 128.59; 126.24; 121.99; 115.84; 112.88; 64.23; 61.98; 61.14; 51.43; 61.14; 51.43; 47.07; 42.81; 29.38; 24.85; 24.11; 21.00; 20.32; 19.30.

HRMS calc. for C₃₁H₄₂N₄O₅ 550.3155; found: 550.3150±0.0016.

HPLC (standard gradient) t_(R)=8.91 min.

Compound 56

Yield: 16 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.39 (b, 1H); 8.90 (b, 1H); 8.67 (d, 1H, 8.4 Hz); 7.74 (b, 4H); 7.29-7.08 (m, 4H); 6.99-6.87 (m, 2H); 6.64 (d, 2H, 8.1 Hz); 6.61 (d, 1H, 16.5 Hz); 6.40 (dt, 1H, 5.7 Hz, 16.5 Hz); 4.40-4.06 (m, 4H); 4.02-3.95 (m, 1H); 3.79 (dd, 1H, 3.6 Hz, 7.8 Hz); 3.55-3.30 (m, 2H); 3.16-3.05 (m, 3H); 2.82-2.69 (m, 2H); 2.02-1.85 (m, 2H); 1.64-1.43 (m, 3H); 1.29-1.23 (m, 1H); 1.01 (d, 3H, 6.3 Hz); 0.91 (d, 3H, 6.3 Hz); 0.86-0.84 (m, 2H).

HPLC (standard gradient) t_(R)=5.71 min.

Compound 65

Yield: 17 mg pure macrocycle was obtained (CLND quantification).

¹H NMR (300 MHz, DMSO-d₆) δ 9.60 (b, 1H); 9.39 (b, 1H); 8.88 (b, 1H); 8.70 (d, 1H, 7.5 Hz); 8.57 (d, 1H, 4.2 Hz); 7.27 (t, 6 Hz); 6.96 (d, 2H, 8.4 Hz); 6.66 (d, 2H, 8.4 Hz); 5.78-5.68 (m, 1H); 5.42-5.33 (m, 1H); 3.96-3.89 (m, 1H); 3.80-3.57 (m, 5H); 3.41-3.34 (m, 1H); 3.10-2.90 (m, 1H); 2.78-2.66 (m, 1H); 2.21-2.10 (m, 1H); 2.06-1.93 (m, 1H); 1.70-1.60 (m, 1H); 1.52-1.41 (m, 1H); 1.39-1.26 (m, 1H); 1.25 (d, 3H, 4.8 Hz); 1.23 (d, 3H, 4.5 Hz); 0.83 (dd, 3H, 3 Hz, 4.5 Hz).

¹³C NMR (75.5 MHz, DMSO-d₆) δ 172.68; 172.63; 159.15; 158.73; 157.38; 157.25; 130.89; 124.99; 116.03; 62.51; 62.12; 54.29; 49.27; 42.47; 32.77; 30.43; 28.85; 20.46; 19.59; 18.72; 17.39; 13.90; 13.09.

HRMS calc. for C₂₄H₃₆N₄O₄: 444.2736; found: 444.2726±0.0013

HPLC (standard gradient) t_(R)=6.80 min.

Compound 144

¹H NMR (300 MHz, CD₃OD) δ 7.4 (m, 1H); 7.27 (dt, 1H, 1.5 Hz, 6.6 Hz); 7.22-7.14 (m, 2H); 7.08-6.98 (m, 2H); 6.78 9t, 2H, 6.6 Hz); 4.45-4.39 (m, 2H); 4.15 (d, 2H, 8.1 Hz); 7.74 (d, 1H, 9.3 Hz); 3.54 (d, 1H, 10.8 Hz); 3.35-3.22 (m, 2H); 3.20 (q, 1H, 1.5 Hz); 2.82-2.71 (m, 1H); 2.61-2.55 (m, 1H); 2.21-2.11 (m, 1h); 2.02-1.94 (m, 1H); 1.74-1.40 (m, 5H); 1.04 (d, 3H, 6.6 Hz); 0.93 (d, 3H, 6.6 Hz); 0.74-0.64 9m, 1H); 0.45-0.28 (m, 2H); 0.15-0.08 (m, 1H); 0.06-0.02 (m, 1H).

¹³C NMR (75.5 MHz, CD₃OD) δ 173.29; 172.14; 167.51; 155.47; 134.86; 134.81; 130.38; 130.31; 128.81; 128.25; 127.44; 121.63; 110.39; 107.71; 105.02; 67.10; 66.66; 62.81; 62.06; 60.10; 53.99; 41.44; 36.07; 31.91; 30.01; 29.18; 28.94; 27.79; 23.68; 23.15; 19.08; 18.25; 8.17; 4.98; 3.16.

HRMS: calc. for C₃₁H₄₁N₄O₄Cl 568.2816; found 568.2802±0.0017

F. Mass Spectral Data for Selected Compounds of the Invention

TABLE 2 Analysis of selected compounds of the invention Molecular Weight Monoisotopic M + H Molecular Formula (calculated) Mass Found 1 C30H40N4O5 536.7 536 537 2 C30H40N4O4 520.7 520 521 3 C30H42N4O4 522.7 522 523 4 C30H42N4O5 538.7 538 539 5 C28H36N4O5 508.6 508 509 6 C30H40N4O5S 568.7 568 569 7 C31H42N4O5 550.7 550 551 8 C34H42N4O5 586.7 586 587 9 C30H40N4O5 536.7 536 537 10 C31H42N4O5 550.7 550 551 11 C34H44N4O4 572.7 572 573 12 C29H38N4O5 522.6 522 523 13 C31H44N4O4 536.7 536 537 14 C35H46N4O4 586.8 586 587 15 C30H41N4O4Cl 557.1 556 557 16 C30H41N4O4Cl 557.1 556 557 17 C32H43N5O4 561.7 561 562 18 C29H40N4O5 524.7 524 525 19 C30H41N4O4F 540.7 540 541 20 C31H42N4O4 534.7 534 535 21 C35H44N4O4 584.7 584 585 22 C31H44N4O5 552.7 552 553 23 C34H44N4O4 572.7 572 573 24 C28H40N4O4S 528.7 528 529 25 C30H41N4O4Cl 557.1 556 557 26 C31H42N4O5 550.7 550 551 27 C27H39N5O4S 529.7 529 530 28 C29H41N5O4 523.7 523 524 29 C28H39N5O5 525.6 525 526 30 C30H41N3O6 539.7 539 540 34 C34H40N4O6 600.7 600 601 38 C28H36N4O5 508.6 508 509 39 C28H36N4O5 508.6 508 509 40 C27H34N4O5 494.6 494 495 41 C34H40N4O5 584.7 584 585 52 C33H38N4O5 570.7 570 571 55 C31H43N5O5 565.7 565 566 56 C30H41N5O5 551.7 551 552 57 C28H36N4O6 524.6 524 525 58 C34H40N4O6 600.7 600 601 59 C36H41N5O5 623.7 623 624 60 C35H42N4O6 614.7 614 615 65 C24H36N4O4 444.6 444 445 71 C29H40N4O6 540.7 540 541 72 C38H42N4O5 634.8 634 635 76 C38H42N4O5 634.8 634 635 77 C31H42N4O5 550.7 550 551 80 C31H42N4O5 550.7 550 551 85 C30H40N4O5 536.7 536 537 87 C36H46N4O4 598.8 598 599 88 C34H50N4O5 594.8 594 595 89 C31H44N4O4 536.7 536 537 90 C36H46N4O4 598.8 598 599 91 C30H42N4O5 538.7 538 539 92 C31H44N4O5 552.7 552 553 96 C28H38N4O5 510.6 510 511 97 C33H46N4O5 578.7 578 579 98 C24H39N5O4 461.6 461 462 99 C24H39N5O4 461.6 461 462 109 C29H41N5O5 539.7 539 540 110 C29H41N5O5 539.7 539 540 111 C30H41N3O6 539.7 539 540 112 C31H44N4O5 552.7 552 553 120 C30H38N4O5 534.6 534 535 121 C32H45N5O6 595.7 595 596 122 C31H43N4O4Cl 571.2 570 571 123 C29H41N5O4 523.7 523 524 124 C29H41N5O4 523.7 523 524 125 C30H40N4O5 536.7 536 537 126 C32H46N4O5 566.7 566 567 127 C30H38N6O3S 562.7 562 563 128 C32H46N4O5 566.7 566 567 129 C35H46N4O4 586.8 586 587 130 C29H42N4O4S 542.7 542 543 131 C31H43N4O4Cl 571.2 570 571 132 C31H43N4O4Cl 571.2 570 571 133 C31H43N4O4F 554.7 554 555 134 C25H37N4O3Cl 477.0 476 477 135 C31H45N5O5 567.7 567 568 136 C34H45N5O4 587.8 587 588 137 C28H41N5O4S 543.7 543 544 138 C30H42N5O4Cl 572.1 571 572 139 C30H42N5O4Cl 572.1 571 572 140 C30H42N5O4F 555.7 555 556 141 C32H44N4O5 564.7 564 565 142 C35H44N4O4 584.7 584 585 143 C29H40N4O4S 540.7 540 541 144 C31H41N4O4Cl 569.1 568 569 145 C31H41N4O4Cl 569.1 568 569 146 C31H41N4O4F 552.7 552 553 147 C31H43N5O5 565.7 565 566 148 C34H43N5O4 585.7 585 586 149 C30H40N5O4Cl 570.1 569 570 150 C30H40N5O4Cl 570.1 569 570 151 C30H40N5O4F 553.7 553 554 152 C29H41N5O5 539.7 539 540 153 C32H41N5O4 559.7 559 560 154 C26H37N5O4S 515.7 515 516 155 C28H38N5O4Cl 544.1 543 544 156 C28H38N5O4Cl 544.1 543 544 157 C28H38N5O4F 527.6 527 528 158 C27H37N6O4Cl 545.1 544 545 159 C31H44N4O5 552.7 552 553 160 C31H44N4O5 552.7 552 553 161 C31H45N5O4 551.7 551 552 162 C31H44N4O4 536.7 536 537 163 C31H44N4O4 536.7 536 537 164 C31H44N4O4 536.7 536 537 165 C31H44N4O5 552.7 552 553 166 C31H44N4O5 552.7 552 553 167 C32H42N4O4S 578.8 578 579 168 C28H40N4O4S 528.7 528 529 169 C31H43N4O4Cl 571.2 570 571 170 C30H40N4O4Cl2 591.6 590 591 171 C30H40N4O4F2 558.7 558 559 172 C32H46N4O6 582.7 582 583 173 C34H43N3O5 573.7 573 574 174 C31H43N3O6 553.7 553 554 175 C31H44N4O5 552.7 552 553 176 C31H44N4O5 552.7 552 553 177 C29H40N4O5 524.7 524 525 178 C29H40N4O6 540.7 540 541 179 C32H40N4O5 560.7 560 561 180 C26H36N4O5S 516.7 516 517 181 C28H37N4O5Cl 545.1 544 545 182 C28H37N4O5Cl 545.1 544 545 183 C28H37N4O5F 528.6 528 529 184 C31H40N6O4 560.7 560 561 185 C27H37N6O4Cl 545.1 544 545 186 C31H40N6O5 576.7 576 577 187 C31H41N4O4F3 590.7 590 591 188 C30H41N4O4F 540.7 540 541 189 C30H41N5O6 567.7 567 568 190 C33H42N4O4S 590.8 590 591 191 C32H44N4O5 564.7 564 565 192 C31H40N4O4Cl2 603.6 602 603 193 C31H40N4O4F2 570.7 570 571 194 C32H48N6O6 612.8 612 613 195 C32H46N4O5 566.7 566 567 196 C32H43N6O4Cl 611.2 610 611 197 C32H45N6O5Cl 629.2 628 629 198 C32H43N4O4Cl 583.2 582 583 199 C27H39N4O6Cl 551.1 550 551 200 C31H39N4O4Cl 567.1 566 567 201 C34H42N4O4 570.7 570 571 202 C31H42N4O5 550.7 550 551 203 C30H40N5O5Cl 586.1 585 586 204 C29H40N7O4Cl 586.1 585 586 205 C32H45N4O4Cl 585.2 584 585 206 C29H40N5O6SCl 622.2 621 622 207 C29H39N6O5Cl 587.1 586 587 208 C29H41N7O5 567.7 567 568 209 C30H41N5O6 567.7 567 568 210 C31H45N5O5 567.7 567 568 211 C30H42N5O4Cl 572.1 571 572 212 C31H44N5O4Cl 586.2 585 586 213 C30H40N4O5I2 790.5 790 791 214 C30H42N4O6 554.7 554 555 215 C30H43N5O5 553.7 553 554 216 C32H43N4O4Cl 583.2 582 583 217 C31H40N4O4FCl 587.1 586 587 218 C31H43N4O4Cl 571.2 570 571 219 C30H40N4O4Cl2 591.6 590 591 220 C31H43N4O4F 554.7 554 555 221 C30H40N4O4FCl 575.1 574 575 222 C34H50N4O5 594.8 594 595 223 C32H44N4O6 580.7 580 581 224 C36H48N4O4 600.8 600 601 225 C37H48N4O5 628.8 628 629 226 C39H49N5O4S 683.9 683 684 227 C42H52N4O4 676.9 676 677 Notes 1. Molecular formulas and molecular weights (MW) are calculated automatically from the structure via ActivityBase ® software (IDBS, Guildford, Surrey, UK) or, for MW only, from the freeware program Molecular Weight Calculator v. 6.32 2. M + H obtained from LC-MS analysis using the General Method as described 3. All analyses conducted on material after preparative HPLC purification

Biological Methods and Results

The compounds of the present invention were evaluated for their ability to interact at the human motilin receptor utilizing a competitive radioligand binding assay as described in Method B1. Further characterization of the interaction can be performed utilizing the functional assays described in Methods B2, B3 and B4. Some of these methods can be conducted, if so desired, in a high throughput manner to permit the simultaneous evaluation of many compounds. Other assays have also been described that are suitable for HTS, such as that based upon the stable expression of a synthetic gene for the human motilin receptor.

Results for the examination of representative compounds of the present invention using Method B1 are presented in Table 3. The binding activity is listed as ranges with the following levels: A=0.001-0.10 μM; B=0.10-1.0 μM; C=1.0-10.0 μM. In addition, the assay results of two additional compounds using this Method are shown below. As can be observed, this demonstrates the activity of a representative bicyclic compound of Formula IV of the invention, which resulted from incorporation of D-proline as the second recognition building block. Significantly, the lack of binding activity obtained with compound 121, which is the linear analogue of compound 1 (K_(i)=level B), illustrates the critical importance of the cyclic structure to attaining the desired interaction.

Competitive binding curves for two representative compounds of the invention (Compounds 8 and 11) are presented hereinbelow:

For determination of functional significance of the binding, the compounds are preferably tested in the Aequorin assay as described in Method B2, although the procedure of Method B3 is also applicable. As can be seen from the data presented in Table 4, the representative compounds examined act as antagonists at the motilin receptor and are devoid of agonist activity at the concentrations studied. The functional activity is listed as ranges with the following levels: A=0.001-0.10 μM; B=0.10-1.0 μM. The higher sensitivity of the assay of Method B2, almost 100 times that of Method C, makes it the preferred one for this assessment. This is evident in the EC₅₀ values obtained in each for the positive agonist standard, motilin. Additionally, Method B2 measures the actual signaling event, which makes it more relevant to the effect that is desired, whereas the assay of Method B3 simply measures GTP turnover.

TABLE 4 Demonstration of Antagonist Activity at the Motilin Receptor Aequorin (Method B2)¹ Compound Binding (K_(i)) IC₅₀ 142 A B 149 A B 167 A A 168 A A 212 A A Motilin 0.6 not applicable (human, porcine)² ¹Activity is listed as ranges with the following levels: A = 0.001-0.10 μM; B = 0.10-1.0 μM ²Human and porClne motilin are the same peptide.

In addition, a common and scientifically-accepted ex vivo assay for the measurement of agonist or antagonist activity at the motilin receptor is the contraction of rabbit duodenum or other gastrointestinal smooth muscle tissue.^(A2-A4) Agonists are defined as compounds that induce >50% contraction relative to the motilin peptide, whereas antagonists are defined as compounds that cause >50% inhibition of the response to motilin. Compounds of the present invention have shown significant antagonist activity in this assay. For example, compound 144 exhibited a pA₂=6.95, while compound 165 had a pA₂=7.17, as calculated from the Schild plots of the response obtained at various concentrations as described in Method B4.

Gastric motility is generally measured in the clinical setting as the time required for gastric emptying and subsequent transit time through the GI tract. Gastric emptying scans are well known to those skilled in the art an, briefly, comprise use of an oral contrast agent, such as barium, or a radiolabeled meal. Solid and liquids can be measured independently. A test food or liquid is radiolabeled with an isotope (^(99m)Tc) and after ingestion or administration, transit time through the GI tract and gastric emptying are measured by visualization using gamma cameras. These studies are performed before and after the administration of the therapeutic agent to quantify the efficacy of the compound.

Example Method B1 Competitive Radioligand Binding Assay (Motilin Receptor) Materials:

-   -   Membranes were prepared from CHO cells stably transfected with         the human motilin receptor and utilized at a quantity of 1.5         μg/assay point. [PerkinElmer™ SignalScreen®) Product #6110544,         PerkinElmer, Inc., Wellesley, Mass.]     -   [¹²⁵I]-Motilin (PerkinElmer, #NEX-378); final concentration:         0.04-0.06 nM     -   Motilin (Bachem™, #H-4385, Bachem Bioscience Inc., King of         Prussia, Pa.); final concentration: 1 μM     -   Multiscreen® Harvest plates-GF/B (Millipore™, #MAHFB1H60,         Billerica, Mass.)     -   Deep-well polypropylene titer plate (Beckman Coulter™, #267006,         Fullerton, Calif.)     -   TopSeal-A™ (PerkinElmer, #6005185, Wellesley, Mass.)     -   Bottom seal (Millipore™, #MATAH0P00, Billerica, Mass.)     -   MicroScint-0™ (PerkinElmer, #6013611, Wellesley, Mass.)     -   Binding Buffer: 50 mM Tris-HCl (pH 7.4), 10 mM MgCl₂, 1 mM EDTA,         0.1% BSA

Assay Volumes:

-   -   150 μL of membranes diluted in binding buffer     -   10 μL of compound diluted in binding buffer     -   10 μL of radioligand ([¹²⁵I]-Motilin) diluted in binding buffer

Final Test Concentrations (N=11) for Compounds:

-   -   10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02, 0.01, 0.005 μM.

Compound Handling:

Compounds were provided frozen on dry ice at a stock concentration of 10 mM diluted in 100% DMSO and stored at −20° C. until the day of testing. On the test day, compounds were allowed to thaw at room temperature and than diluted in assay buffer according to the desired test concentrations. Under these conditions, the maximum final DMSO concentration in the assay was 0.5%.

Assay Protocol:

In deep-well plates, diluted cell membranes (1.5 μg/mL) are combined with 10 μL of either binding buffer (total binding, N=5), 1 μM motilin (non-specific binding, N=3) or the appropriate concentration of test compound. The reaction is initiated by addition of 10 μl of [¹²⁵I]-motilin (final conc. 0.04-0.06 nM) to each well. Plates are sealed with TopSeal-A, vortexed gently and incubated at room temperature for 2 hours. The reaction is arrested by filtering samples through pre-soaked (0.3% polyethyleneimine, 2 h) Multiscreen Harvest plates using a Tomtec® Harvester (Tomtec, Hamden, Conn.)), washed 9 times with 500 μL of cold 50 mM Tris-HCl (pH 7.4), and than plates are air-dried in a fumehood for 30 minutes. A bottom seal is applied to the plates prior to the addition of 25 μL of MicroScint-0™ to each well. Plates are then sealed with TopSeal-A® and counted for 30 sec per well on a TopCount® Microplate Scintillation and Luminescence Counter (PerkinElmer, Wellesley, Mass.) where results are expressed as counts per minute (cpm).

Data are analyzed by GraphPad™ Prism (GraphPad Software, San Diego, Calif.) using a variable slope non-linear regression analysis. K_(i) values were calculated using a K_(d) value of 0.16 nM for [¹²⁵I]-motilin (previously determined during membrane characterization).

$D_{\max} = {1 - {\frac{\begin{matrix} {{{test}\mspace{14mu} {concentration}\mspace{14mu} {with}\mspace{14mu} {maximal}\mspace{14mu} {displacement}} -} \\ {{non}\text{-}{specific}\mspace{14mu} {binding}} \end{matrix}}{{{total}\mspace{14mu} {binding}}\; - \; {{non}\text{-}{specific}\mspace{14mu} {binding}}} \times 100}}$

where total and non-specific binding represent the cpm obtained in the absence or presence of 1 μM motilin, respectively.

Example Method B2 Aequorin Functional Assay (Motilin Receptor) Materials:

-   -   Membranes were prepared using AequoScreen™ (EUROSCREEN, Belgium)         cell lines expressing the human motilin receptor (cell line         ES-380-A; receptor accession #AF034632). This cell line is         constructed by transfection of the human motilin receptor into         CHO-K1 cells co-expressing G_(α16) and the mitochondrially         targeted Aequorin (Ref #ES-WT-A5).     -   Motilin (Bachem™, #H-4385, Bachem Bioscience Inc., King of         Prussia, Pa.)     -   Assay buffer: DMEM-F12 (Dulbeccoe's Modified Eagles Medium) with         15 mM HEPES and 0.1% BSA (pH 7.0)     -   Coelenterazine (Molecular Probes™, Leiden, The Netherlands)

Final Test Concentrations (N=5) for Compounds:

-   -   10, 3.16, 1, 0.316, 0.1 μM.

Compound Handling:

Compounds were provided as dry films at a quantity of approximately 1.2 mmol in pre-formatted 96-well plates. Compounds were dissolved in 100% DMSO at a concentration of 10 mM and stored at −20° C. until further use. Daughter plates were prepared at a concentration of 500 μM in 30% DMSO with 0.1% BSA and stored at −20° C. until testing. On the test day, compounds were allowed to thaw at room temperature and than diluted in assay buffer according to the desired test concentrations. Under these conditions, the maximum final DMSO concentration in the assay was 0.6%.

Cell Preparation:

Cells are collected from culture plates with Ca²⁺ and Mg²⁺-free phosphate buffered saline (PBS) supplemented with 5 mM EDTA, pelleted for 2 minutes at 1000×g, resuspended in assay buffer (see above) at a density of 5×10⁶ cells/mL and incubated overnight in the presence of 5 μM coelenterazine. After loading, cells were diluted with assay buffer to a concentration of 5×10⁵ cells/mL.

Assay Protocol:

For agonist testing, 50 μl of the cell suspension was mixed with 50 μl of the appropriate concentration of test compound or motilin (reference agonist) in 96-well plates (duplicate samples). The emission of light resulting from receptor activation was recorded using the Functional Drug Screening System 6000 ‘FDSS 6000’ (Hamamatsu Photonics K.K., Japan).

For antagonist testing, an approximate EC80 concentration of motilin (i.e. 0.5 nM; 100 μL) was injected onto the cell suspension containing the test compounds (duplicate samples) 15-30 minutes after the end of agonist testing and the consequent emission of light resulting from receptor activation was measured as described in the paragraph above.

Results are expressed as Relative Light Units (RLU). Concentration response curves were analyzed using GraphPad™ Prism® (GraphPad Software, San Diego, Calif.) by non-linear regression analysis (sigmoidal dose-response) based on the equation E=E_(max)/(1+EC₅₀/C)n where E is the measured RLU value at a given agonist concentration (C), E_(max) is the maximal response, EC₅₀ is the concentration producing 50% stimulation and n is the slope index. For agonist testing, results for each concentration of test compound were expressed as percent activation relative to the signal induced by motilin at a concentration equal to the EC₈₀ (i.e. 0.5 nM). For antagonist testing, results for each concentration of test compound were expressed as percent inhibition relative to the signal induced by motilin at a concentration equal to the EC₈₀ (i.e. 0.5 nM).

Example Method B3 FlashPlate® Motilin [³⁵S]-GTPγS Functional Assay Materials:

-   -   Membranes were prepared from CHO cells stably transfected with         the human motilin receptor and utilized at a quantity of 1.5         μg/assay point.     -   [PerkinElmer™ SignalScreen® Product #6110544, PerkinElmer, Inc.         Wellesley, Mass.]     -   GTPγS Guanosine 5′-[γ-thio]triphosphate tetralithium salt         (Sigma, #G-8634, Sigma-Aldrich, St. Louis, Mo.)     -   [³⁵S]-GTPγS (PerkinElmer, #NEX-030H)     -   Motilin (Bachem™, #H-4385, Bachem Bioscience Inc., King of         Prussia, Pa.)     -   96-well FlashPlate® white polystyrene microplates (PerkinElmer,         #SMP200, Wellesley, Mass.)     -   Deep-well polypropylene titer plate (Beckman Coulter™, #267006,         Fullerton, Calif.)     -   TopSeal-A™ (PerkinElmer, #6005185, Wellesley, Mass.)     -   Assay Buffer: 50 mM Tris (pH 7.4), 100 mM NaCl, 10 mM MgCl₂, 1         mM EDTA, 1 μM GDP, 0.1% BSA

Assay Volumes:

-   -   25 μL of compound diluted in assay buffer     -   25 μL of assay buffer (agonist assay) or 0.6 μM motilin (0.1 μM         final concentration) diluted in assay buffer (antagonist assay)     -   100 μL of [³⁵S]-GTPγS diluted in assay buffer

Final Test Concentrations (N=12) for Compounds:

-   -   50, 20, 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.02, 0.01 μM.

Compound Handling:

Compounds were provided frozen on dry ice at a stock concentration of 10 mM diluted in 100% DMSO and stored at −20° C. until the day of testing. On the test day, compounds were allowed to thaw at room temperature and than diluted in assay buffer according to the desired test concentrations. Under these conditions, the maximum final DMSO concentration in the assay was 0.5%.

Assay Protocol:

CHO membranes were immobilized into 96-well FlashPlate® microplates. Test compound, GTPγS, motilin and [³⁵S]-GTPγS were combined in each well according to the Assay Volumes described above.

For the assay to measure agonist activity, an additional 25 μl of buffer was added to each well in addition to 25 μL of either buffer (basal value, N=4), 1 μM (final conc.) motilin (E_(max) value, N=3), 25 μM (final conc.) GTPγS (non-specific value, N=4), or the appropriate concentration of test compound (N=3).

For the assay to measure antagonist activity, an additional 25 μL of either buffer (unstimulated control) or motilin (0.1 μM final conc.) is added to each well, in addition to either 25 μL of buffer (basal value, N=3), 1 μM (final conc.) motilin (E_(max) value, N=3), 25 μM (final conc.) GTPγS (non-specific value, N=4), or the appropriate concentration of test compound (N=3).

The reaction is initiated by addition of 100 mL of [³⁵S]-GTPγS to each well. Each plate is sealed (TopSeal-A™) and incubated in the dark at room temperature for 150 min. Then, plates are counted for 30 seconds per well on the TopCount® NXT.

Data were analyzed by GraphPad™ Prism® 3.0 (GraphPad Software, San Diego, Calif.) using non-linear regression analysis (sigmoidal dose-response) for the calculation of IC₅₀/EC₅₀ values.

${{E_{\max}({agonist})}\mspace{14mu} {or}\mspace{14mu} {D_{\max}({antagonist})}} = {\frac{{Top} - {Bottom}}{Bottom} \times 100}$

Where Top and Bottom correspond to the top and bottom values of the dose-response curve calculated by GraphPad™ Prism®).

Example Method B4 Rabbit Duodenum Contractility Assay

Duodenal segments were vertically suspended in organ chambers of 10 mL filled with Krebs buffer and connected to an isotonic force transducer, with a preload of 1 g. After a stabilization period, the muscle strips were challenged with 10⁻⁴ M acetylcholine and washed. This was repeated until a stable maximal contraction was obtained (2-3 times), with an interval of at least 20 minutes.

After a stable base line was reached, test compounds were added to the bath. After 15 min incubation, a dose response to motilin was recorded by adding logarithmically increasing concentrations of motilin to the bath (final concentration 10⁻⁹ to 10⁻⁶ M). A blank experiment (no test compound present) was also performed. At the end of the dose response curve, a supramaximal dose of acetylcholine (10⁻⁴ M) was given and this response was used as a reference (100% contraction).

The results of experiments at different concentrations of test compound were combined and analyzed to derive the pA₂ value from the Schild plot.

It is appreciated that although specific experimental methods have been described herein for the purposes of illustration, various modifications to these experimental methods as well as alternate methods of experimentation may be used without departing from the scope of this invention.

TABLE 3 Binding activity of selected compounds R₁ R₃ R₆ 1

2

3

4

5

CH3

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

34

38

CH₃ 39

H 40

H 41

52

55

56

57

58

59

60

65

71

72

76

77

80

85

H 87

88

89

90

91

92

96

H

97

98

99

109

110

111

112

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

T K_(i) ^(1,2) 1

B 2

A 3

B 4

A 5

B 6

B 7

B 8

B 9

B 10

A 11

A 12

B 13

B 14

B 15

A 16

A 17

B 18

B 19

A 20

B 21

A 22

A 23

A 24

A 25

B 26

A 27

B 28

B 29

B 30

B 34

B 38

C 39

B 40

C 41

C 52

B 55

B 56

B 57

B 58

B 59

B 60

C 65

B 71

B 72

B 76

C 77

C 80

B 85

B 87

B 88

C 89

C 90

C 91

C 92

B 96

C 97

C 98

C 99

C 109

B 110

B 111

B 112

B 122

B 123

B 124

B 125

B 126

B 127

B 128

B 129

A 130

B 131

A 132

A 133

A 134

C 135

B 136

B 137

B 138

B 139

B 140

B 141

A 142

A 143

B 144

A 145

A 146

A 147

B 148

B 149

A 150

B 151

B 152

B 153

B 154

B 155

A 156

A 157

B 158

A 159

B 160

B 161

B 162

B 163

A 164

B 165

A 166

B 167

A 168

A 169

B 170

A 171

A 172

A 173

B 174

B 175

B 176

B 177

B 178

B 179

B 180

B 181

A 182

A 183

B 184

B 185

B 186

B 187

A 188

A 189

B 190

A 191

A 192

A 193

A 194

B 195

A 196

197

198

A 199

B 200

A 201

B 202

A 203

B 204

A 205

B 206

B 207

B 208

B 209

C 210

211

A 212

A 213

B 214

B 215

B 216

A 217

B 218

A 219

B 220

A 221

B 222

A 223

C 224

B 225

B 226

C 227

B Notes Radioligand competitive binding assays performed using Method B1 Values reported as ranges: A = 0.001-0.100 μM; B = 0.100-1.0 μM; C = 1.0-10.0 μM

X is NH except for:

Compound 223 and 225, X is:

Compound 224, X is NMe

Compound 226, X is:

Compound 227, X is

Z₁, Z₂ and Z₃ are NH except for compounds 30, 173 and 174 and where Z1 is O and compound 111 where Z₂ is O.

R₂, R₄ and R₅ are hydrogen except for compound 85 where it is:

m, n₁ and p are zero. 

1. A process for preparing a compound of formula (I):

wherein R₁ is C₁-C₄ alkyl; the process comprising: (a) contacting a compound of formula (A):

with a compound of formula (B):

in the presence of an azodicarboxylate reagent and a phosphine reagent, or in the presence of a combined Mitsunobu reagent, to form a compound of formula (C):

wherein X is halogen or triflate and PG₂ is an ester protecting group; (b) contacting the compound of formula (C) with a reducing agent to form a compound of formula (D):

(c) contacting the compound of formula (D) with a compound of formula (E):

in the presence of a palladium catalyst, optionally a copper salt and/or optionally an organic base to form a compound of formula (F):

wherein PG₁ is hydrogen or an amine protecting group; (d) contacting the compound of formula (F) with hydrogen in the presence of a metal catalyst to form the compound of formula (G):

(e) removing the PG₁ protecting group, when present, from the compound of formula (G) to provide the compound of formula (I).
 2. The process of claim 1, wherein the compound of formula (I) is:


3. The process of claim 1 wherein the compound of formula (B) is selected from the group consisting of:

wherein PG₂ is an ester protecting group.
 4. The process of claim 1, wherein X is iodine.
 5. The process of claim 1, wherein PG₁ is hydrogen.
 6. The process of claim 1, wherein PG₁ is a carbamate protecting group.
 7. The process of claim 1, wherein PG₁ is selected from the group consisting of tert-butoxycarbonyl (Boc), benzyloxycarbonyl (Cbz), 9-fluorenyl methoxycarbonyl (Fmoc), α,α-dimethyl-3,5-dimethoxybenzyloxycarbonyl (Ddz) and allyloxycarbonyl (Alloc).
 8. The process of claim 1, wherein PG₂ is an alkyl group or an alkyl group substituted with an aryl group.
 9. The process of claim 1, wherein PG₂ is methyl, ethyl or benzyl.
 10. The process of claim 1, wherein the azodicarboxylate reagent is selected from the group consisting of diethylazodicarboxylate (DEAD) and diisopropylazodicarboxylate (DIAD).
 11. The process of claim 1, wherein the phosphine reagent is selected from the group consisting of triphenylphosphine and tributylphosphine.
 12. The process of claim 1, wherein the combined Mitsunobu reagent is a triphenylphosphine-diisopropylazodicarboxylate (DIAD) adduct.
 13. The process of claim 1, wherein the reducing agent is selected from the group consisting of an aluminum hydride and a borohydride.
 14. The process of claim 1, wherein the reducing agent is selected from the group consisting of diisobutylaluminum hydride (DIBAL-H), lithium aluminum hydride (LAH), and lithium borohydride.
 15. The process of claim 1, wherein the palladium catalyst is selected from the group consisting of dichlorobis(triphenylphosphine)palladium(II), dichlorobis(acetonitrile)-palladium(II), dichlorobis(benzonitrile)palladium(II), tetrakis(triphenyl-phosphine)palladium(0) and tris(dibenzylideneacetone)dipalladium(0).
 16. The process of claim 1, wherein the copper salt is a copper halide.
 17. The process of claim 1, wherein the copper salt is copper (I) iodide.
 18. The process of claim 1, wherein the copper salt is not present.
 19. The process of claim 1, wherein the organic base is selected from the group consisting of a dialkylamine, a trialkylamine and an aromatic amine.
 20. The process of claim 1, wherein the organic base is triethylamine (TEA), diisopropylamine or N,N-diisopropylethylamine (DIPEA).
 21. The process of claim 1, wherein the organic base is not present.
 22. The process of claim 1, wherein (c) is conducted in the presence of a phosphine.
 23. The process of claim 1, wherein the metal catalyst is palladium on carbon or platinum oxide.
 24. The process of claim 1 further comprising one or more purification steps.
 25. The process of claim 1, wherein contacting the compound of formula (A) with a compound of formula (B) in the presence of an azodicarboxylate reagent and a phosphine reagent, or in the presence of a combined Mitsunobu reagent, to form a compound of formula (C) is replaced by contacting the compound of formula (A) with a compound of formula (G):

wherein Y is a leaving group, R₁ is C₁-C₄ alkyl and PG₇ is an ester protecting group, in the presence of a base to form the compound of formula (C).
 26. The process of claim 25, wherein Y is a halogen or a sulfonate.
 27. The process of claim 25, wherein Y is selected from the group consisting of 4-methylbenzenesulfonate (tosylate), methanesulfonate (mesylate), 2-nitrobenzenesulfonate, 4-nitrobenzenesulfonate (nosylate), 2,4-dinitrobenzenesulfonate, 4-bromobenzenesulfonate (brosylate), trifluoromethanesulfonate (triflate), chloride, bromide and iodide.
 28. The process of claim 25, wherein the base is selected from the group consisting of a hydrogen carbonate salt, a carbonate salt, a trialkylamine and an aromatic amine.
 29. A process for preparing a compound of formula (G):

wherein R₁ is C₁-C₄ alkyl and PG₁ is an amine protecting group; the process comprising: (a) contacting a compound of formula (A):

with a compound of formula (B):

in the presence of an azodicarboxylate reagent and a phosphine reagent, or in the presence of a combined Mitsunobu reagent, to form a compound of formula (C):

wherein X is halogen or triflate and PG₂ is an ester protecting group; (b) contacting the compound of formula (C) with a reducing agent to form a compound of formula (D):

(c) contacting the compound of formula (D) with a compound of formula (E):

in the presence of a palladium catalyst, optionally a copper salt and/or optionally an organic base to form a compound of formula (F):

(d) contacting the compound of formula (F) with hydrogen in the presence of a metal catalyst to form the compound of formula (G).
 30. A compound of formula (II):

wherein R₁ is C₁-C₄ alkyl; X is halogen or triflate; and PG₃ is hydrogen or an ester protecting group.
 31. The compound of claim 30, wherein X is iodine.
 32. The compound of claim 30, wherein R₁ is methyl.
 33. The compound of claim 30, wherein PG₃ is alkyl.
 34. The compound of claim 30 represented by the following structures:

wherein PG₃ is hydrogen or an ester protecting group.
 35. A compound of formula (III):

wherein R₁ is C₁-C₄ alkyl; X is halogen or triflate; and PG₄ is hydrogen or a hydroxy protecting group.
 36. The compound of claim 35, wherein X is iodine.
 37. The compound of claim 35, wherein R₁ is methyl.
 38. The compound of claim 35, wherein PG₄ is hydrogen.
 39. The compound of claim 35 represented by the following structures:

wherein PG₄ is hydrogen or a hydroxy protecting group.
 40. A compound of formula (IV):

wherein R₁ is C₁-C₄ alkyl; PG₅ is hydrogen or an amine protecting group; and PG₆ is hydrogen or a hydroxy protecting group.
 41. The compound of claim 40, wherein R₁ is methyl.
 42. The compound of claim 40, wherein PG₅ is hydrogen.
 43. The compound of claim 40, wherein PG₅ is a carbamate protecting group.
 44. The compound of claim 40, wherein PG₅ is selected from the group consisting of tert-butoxycarbonyl (Boc), benzyloxycarbonyl (Cbz), 9-fluorenyl methoxycarbonyl (Fmoc), α,α-dimethyl-3,5-dimethoxybenzyloxycarbonyl (Ddz) and allyloxycarbonyl (Alloc).
 45. The compound of claim 40, wherein PG₆ is hydrogen.
 46. The compound of claim 40 represented by the following structures:

wherein PG₅ is hydrogen or an amine protecting group; and PG₆ is hydrogen or a hydroxy protecting group. 